Method for making composite twine structures

ABSTRACT

A composite structure comprises at least one ply comprising approximately parallel unidirected twines comprising helically-configured matrix-impregnated continuous strands of filament reinforcements to provide a flanged composite cantilever spring which serves as the principal constituent of a coupling structure. An interior ply of a coupling structure body member comprises unidirected longitudinal twines configured at a body member extremity to provide a flange member connected to a cantilever spring. An exterior ply is disposed transversely of and superimposed upon the interior ply to provide the cantilever spring hinge line. The composite cantilever spring can be constructed to deflect about either a straight or curved hinge line. A preferred tubular form of the coupling structure comprises at least one end configured as a polygonal array of flanged cantilever springs which serve as the socket end of a spring-lock coupling used to connect mating flanged spigot-end structures. A preferred segmented form of coupling structure comprises two semi-circular flanged cantilever spring members assembled and deflected by an encircling retaining sleeve. 
     The method and apparatus for making a composite in the form of a preferred coupling structure comprises placing first ply loops of longitudinal twines upon a pin-ended forming surface, transversely placing a second ply of twines upon the first ply twines to deflect them into flange-forming cavities, hardening the twine-impregnating matrix, removing and slotting the flanged spring members to provide the desired coupling structure.

This is a division of Ser. No. 716,565 filed Mar. 27, 1985, now U.S.Pat. No. 4,680,923.

DESCRIPTION

1. Technical Field

This invention relates to a multiple ply flanged composite cantileverspring coupling structure and method and apparatus for making same. Theinvention relates particularly to a coupling structure consisting of atleast one flanged composite cantilever spring member formed from amultiple ply composite structure comprising at least two biaxialunidirectional plies of tensioned twines, where each twine consists of amultiple of helically-configured continuous filament strands impregnatedwith a hardenable liquid matrix. An interior body member ply comprises aunitary structure comprising twines of the helically configured strandsaligned parallel to each other and configured at a body member extremityto provide a flange member connected to a composite cantilever springmember. An outer ply comprises pretensioned twines disposed transverselyof and superimposed upon only the interior ply of the body and flangemembers. The first and second plies are each oriented perpendicular tothe direction of the composite spring deflection. One form of a desiredcoupling structure comprises a tubular multiple ply composite bodystructure having a body extremity with an inner surface shaped as aregular polygon and partially slotted at the polygon corner edges toprovide an annular array of inwardly-flanged flat composite cantileverspring members, each of which can be independently deflected outwardlyabout a straight hinge line to provide a flanged spring locking couplingstructure which serves as a deflectable socket end to connect a matingspigot-end structure having an outwardly directed flange.

Another form of a desired coupling structure comprises a semi-circularmultiple ply composite body structure the extremities of which comprisea curved hinge cantilever spring connected to an inwardly directedcurved flange having a load face and surface formed from the sameunidirectional longitudinal ply of twines used to make the bodystructure. The structure provides one of two identica1 coupler halveswhich are assembled and held together by a removable clamp or tubularsleeve which deflects the curved flanged cantilever springs and providesa coupling between joint-ended structures having external matingflanges.

1. BACKGROUND

Composites consist of one or more discontinuous phases, such as filamentreinforcements, embedded in a continuous phase, such as a thermosettingresin matrix. Composite materials offer a way to improve mechanicalproperties such as strength, stiffness, toughness and high temperatureperformance. Properties of composites are strongly influenced by theproperties of their constituent materials, their distribution and theinteraction among them. In describing a composite material, besidesspecifying the constituent materials and their properties, one needs tospecify the geometry of the reinforcement with reference to the system.The geometry of the reinforcement may be described by the shape, sizeand size distribution. The composite material of the present inventioncomprises continuous filaments as the reinforcement or discontinuousphase and a hardenable liquid matrix as the continuous phase. Thegeometry of the reinforcements employed in the present invention can bedescribed as continuous filaments of uniform diameter havingmanufactured lengths of several hundred meters and filament diameterstypically ranging from 7 microns (0.00028 in.) to 25 microns (0.001in.). The concentration of the filament reinforcements comprising thecomposite material of the present inventions typically ranges from 45 to60 percent by volume. The composite material of the present inventionmost closely resembles the class of composites known as unidirectionalcomposites.

An important mechanical property and design parameter of unidirectedcomposite materials is herein referred to as the "transverse shearstrength". This property is the shear strength of a bundle of filamentstrands held together by a hardened matrix. It is also referred to asthe "across strand" shear strength, the value of which can be determinedby the ASTM test method D-732 which uses a punch type shear tool and acomposite structure test specimen measuring 2"×2" and comprising asingle thickness of filament strands oriented approximately parallel toeach other. The composite structure test specimen is clamped between thepunch holder so that the filaments are oriented at right angles to thepunch face. Shear strength tests performed by ASTM D-732 method showthat the transverse shear strength of a single ply of a unidirectedtwined strand composite comprising sinusoidally oriented glass filamentreinforcements impregnated with a hardenable polyester resin matrixranges from 172 to 241 MN/m² (25,000 to 35,000 PSI). This substantiallyexceeds the interlaminar "in plane" shear strength of conventinalreinforced thermosetting plastics determined by ASTM D-3846.

It is necessary to distinguish a unidirectional "ply" from aunidirectional "laminate" if the discoveries disclosed in the presentinvention are to be clearly understood. Prior art unidirectionallaminates, such as comprise prior art filament wound and pre-preg ribbonlayered composites, are constructed not from individual filaments butfrom "tows" or "strands" containing numerous filaments. It is well knownthat each filament strand or tow contains hundreds and often thousandsof individual filaments which, especially in the case of the glassfilament strands called "roving", are not exactly parallel to each otherbut are twisted in a loose untangled manner after being coated with adissolvable fiber size that converts the bundle of filaments into astrand to provide what is referred to as strand integrity. These strandsof glass filaments are wound onto a collet to form a primary package or"cake" to facilitate their use in filament winding and pultrusionoperations. Typically these "cakes" or roving packages are hollowcylinders that enable the strands to be fed by pulling from the centeror interior of the package in order to eliminate mounting and rotatingthe roving package while the filament strand is fed or pulled from theroving package. Such center pull operations impart a further twist tothe filaments contained in the strand. The amount of strand twist isgoverned by the roving package size as well as the "way wind" numberused in making the package. Generally the "way wind" number is between2.7 and 4.1 which means that for a 6 inch inside diameter cake thefilaments are twisted completely 360° at least once for each meter ofstrand pulled from the roving package. Unless corrected, this strandtwist serves to reduce by as much as half the optimum tensile strengthattainable from unidirectional laminates fabricated from untwistedstrands. This is due to the fact that in a twisted strand the individualfilament lengths resisting a tensile load are not exactly equal and thusonly the shortest length filaments are those that primarily resist atensile load. Because carbon and aramid filament reinforcement is fromfive to thirty times more expensive than glass filament reinforcementthe strands of carbon and aramid filament are made, packaged anddispensed in a manner that reduces the twist and strength loss of carbonand aramid filament strands.

An idealized unidirectional composite is one which consists of paralleluntwisted continuous filaments embedded in a matrix. A prior art"laminate ply" results when two or more unidirectional layers arestacked in a specified sequence of orientation to fabricate a compositestructure. Each layer of unidirectional twined strands discussed in thepresent invention is referred to as a "ply" to distinguish it from priorart stacks of thin laminates which are conventionally referred to as a"laminate ply". A "ply" is herein defined as made from one or moretensioned and unidirected approximately parallel "twines". A "twine" isherein defined as comprising three or more unidirected filament strandstwisted together to provide a sinusoidal wave-like configuration to eachstrand. A ply made from twined strands typically has a thickness tofilament diameter ratio of at least fifty whereas a typical prior artunidirectional composite "laminate" comprises untwisted parallel strandsand has a thickness to filament diameter ratio ranging from ten toforty. The ideal orientation of the sequence of plies made fromunidirectional sinusoidally configured twined strands described in thisinvention is either 0° or 90° with respect to each other with amanufacturing deviation that approximates plus or minus 10°.

Prior art unidirectional composite tubular laminates made byconventional filament winding apparatus and method are fabricated by useof strand feed, impregnation and strand placement techniques thatendeavor to minimize the twist of filaments and filament-containingstrands and thereby minimize the concomitant loss of laminate tensilestrength resulting from twisted filament strand reinforcements. Theunidirectional twined strand composite plies of the present inventionare constructed by methods and with apparatus that intentionallyincreases rather than decreases twisting of the unidirectional filamentreinforcements to provide the desired sinusoidal orientation of thestrand filaments. The reason is most clearly understood when it isrealized that, although important, tensile strength is not the onlyproperty required of a unidirectional composite, especially if thecomposite is to serve as a spring or a frequently flexed structure. Thisinvention teaches that the sinusoidal wave-like arrangement of twinedfilament strands not only greatly increases the stiffness of aunidirectional composite ply structure made therefrom but also greatlyfacilitates the fabrication of tubular composites constructed from twoor more biaxial plies.

Prior art composite tubular structures subjected to free-end closurepressure stress (ASTM D-1598 and D-2992) are constructed in a mannerthat requires the tubular wall structure to simultaneously resistlongitudinal and circumferential stresses. In composite pressurevessels, such as closed-end pipe, the circumferential hoop stress,S_(C), is always double the longitudinal end load stress, S_(L), and iscalculated from the formula S_(C) =PD/2t_(c) ; S_(L) =PD/4t_(c) where"P" is the internal pressure to which the tube is subjected, "D" is theoutside diameter of the tube, "t_(c) " is the proportional thickness ofthe tube wall material which resists the circumferential stress, and"t_(L) " is the proportional thickness of the tube wall material whichresists the longitudinal stress. This invention teaches that a single"CIRC" ply of circumferentially disposed twines having a thickness,"t_(c) ", and constructed upon an impermeable tubular membrane cancomprise the tube wall material used to resist the circumferential tubehoop stress, "S_(C) ", and that a single "LONGO" ply of longitudinallydisposed twines having a thickness "t_(L) " and constructed upon theCIRC ply can comprise the tube wall material used to resist the tube endload longitudinal stress, "S_(L) ".

Prior art composite tubular structures used as pressure vessels exhibita change in overall length and diameter that greatly depends upon thebehaviour of the matrix material bonding together the individuallaminate plies. Theoretically, the change in tube diameter "ΔD" of suchprior art structures having a diameter, "D", can be calculated from theformula: ΔD=ε_(c) D where ε_(c) =S_(c) /E_(c) and is the circumferentialstrain value produced by the hoop stress, "S_(c) ", in a composite tubematerial having a tensile modulus equal to "E_(c) ". In a simalar mannerthe change in tube length, "ΔL" of such prior art structures having alength, "L", can theoretically be calculated from the formula ΔL=ε_(L) Lwhere ε_(L) =S_(L) /E_(L) and is the longitudinal strain value producedby the longitudinal stress, "S_(L) ", in a composite tube materialhaving a tensile modulus equal to "E_(L) ". Unfortunately, the tensilemodulus values E_(c) and E_(T) for prior art composite tube laminate plymaterials are unpredictably influenced by the tensile modulus values andthe Poisson ratio values of the matrix materials used to bond togetherthe laminate plies. For this reason, the location and magnitude of thechanges in length and diameter of prior art composite laminate tubes,especially those constructed of a multitude of helically disposedlaminate ribbons of unidirectional filament strands, cannot be reliablypredicted or calculated.

The present invention teaches that by use of twines of helicallyconfigured strands which are placed adjacent to each other and separatedby a compatible interface material having a tensile strength less thanor equal to the nardened bonding matrix used to impregnate and bondtogether the helically configured twine strands, the location andmagnitude of the changes in diameter and length of a pressurizedcomposite tube structure can be reliably predicted and calculated.

The structural integrity of prior art composite structures made frommultiple layers of unidirected filament laminates is governed by theintegrity of the matrix material used to bond the laminates together.For this reason prior art composite structures degrade in performanceover time as the bonding strength of matrix material is reduced by themicro fractures between the matrix layer and the laminate resulting fromcyclic stresses. The micro fractures in the laminate bonding matrix notonly reduce the peel strength and interlaminar shear strength of thematrix but also promote filament bundle wicking by exposing edges andsurfaces of the laminate to liquids, vapors or gases.

This invention teaches that a substantial increase in compositestructure durability results when the structure is made of twine plieswhich comprise helically configured strands. The twine strand helicalconfiguration disclosed in this invention provides a means for compositestructures to be independent of the interlaminar shear strength, peelstrength, and micro fractures associated with the matrix material usedto impregnate and bond together the filament reinforcements, and therebyexperience substantially less degradation in stiffness and otherphysical properties.

With the advent of high pressure composite pipe which can be rapidly andmechanically joined to provide a permanently sealed connection it is nolonger necessary for pipe engineers to depend exclusively upon weldedsteel pipe as the most reliable and economical method to transportwater, oil, gas and slurry products. In addition to such features ashigh strength to weight and long term resistance to cyclic fatigue andcorrosion, composite pipe has an extremely smooth inner surface whichreduces fluid flow friction and thus lowers the cost to pump productthrough the pipe.

The single most important feature that governs economic comparisonsamong pipe of equivalent linear foot cost and performance is the methodused to join and seal the pipe. Steel pipe is most economically joinedand sealed by welding rather than by use of bolted flanges or threadedcouplings. Composite pipe on the other hand is most economically joinedand sealed by use of mechanical couplings rather than by use offield-bonded connections. The speed and ease by which modern compositepipe can be coupled and sealed as well as uncoupled and removed providesit an economic merit that compares favorably with mechanically coupledsteel pipe.

Modern composite mechanical couplings provide a rapid and reliablemethod of connecting composite pressure pipe. Seals made of modernelastomer materials provide a sealing permanence and integrityequivalent to that of bonded or welded connections. Composite mechanicalcouplings which use threaded joints or bolted flanges are more expensivethan those which employ shallow non-bolted flanges. For this reason,increased attention has been given to the use of coupling structureswhich engage grooves machined in the ends of composite pipe. Suchcoupling structures generally comprise inwardly flanged members such asemployed by Victaulic type clamps. Flexible steel cable or plastic rodused as flexible keys engage shallow recessed flanges or key waysmachined into composite pipe joint ends provide another commonly usedmethod of mechanically coupling composite pipe. Prior art mechanicalcouplings which employ shallow flanges provided by recessed groovesmachined in the conventional laminate ply composite pipe joint ends arelimited in joint tensile strength to the matrix dependent interlaminar"in plane" shear strength of the composite material and for this reasonhave limited the attainable joint strength of prior art composite pipejoints and mating composite mechanical coupling structures. The couplingstructures of the present invention provide a means to overcome priorart coupling strength limits.

A structural flange is a protuberance that enables the transfer of aload from one body to another. For stress analysis purposes a structuralflange can be treated as a short cantilever beam permanently attached toa body which resists the load imposed on the flange. Flanged structuresseldom act singly but generally perform cooperatively with anotherflanged structure to provide a coupling and exchange of load betweenseparate structures. Flanged structures are most commonly employed totransfer tensile, compressive and torsion loads. Torsion loads appliedto prior art composite structures are primarily limited by the low shearstrength of the composite matrix material used to bond a torqued flangeto the surface of the torque-resisting body. The torque resistingcoupling of the present invention overcomes such prior art limitationsby making use of the high transverse shear strength of unidirectedlongitudinal twined strand cords. Flanges which primarily resist tensileand compressive loads imparted to the flange face behave as uniformlyloaded cantilever beams. These tensile and compressive loads impartbending moment stress as well as shear stresses to the materialconnecting the flange to the load resisting body. This invention teachesthat flanges attached to an integral composite cantilever spring aresuperior to prior art coupling structures by providing flangeconstruction which not only reduce the bending moment stress at theflange connection but also increases the strength of the flangeconnection. An objective of the present invention is thus to teach how acomposite flange attached to a composite structure can be constructed tolower the bending moment stress imposed at the flange connection whileconcomitantly increasing the strength of the flange connection toprovide a flanged composite structure superior to prior art compositecouplings.

Prior art composite pipe couplings have been developed which employsegmented spring-loaded curved square shaped keys that engage groovedcomposite pipe joint ends to provide an automatic quick connect typecoupling. Such spring action is provided by independent memberscontained within a socket-end groove constructed within a composite pipejoint. Such spring-action type composite couplings employ flange membersthat act independently as movable shear keys and are constructedseparately from the spring members. Such prior art automatic couplingsare limited in scope and application by the spring member reliability aswell as the shear key and grooved flange in-plane shear strength.

A cantilever spring is a structural member which exhibits a predictabledeflection when subjected to a known load and which returns to itsoriginal position when the load is removed. The present inventionteaches a method of making and using a composite cantilever spring whichpossesses greater fatigue life and spring stiffness for a given springthickness than prior art composite springs.

Prior art composite springs, which usually are not flanged, comprisemultiple layers of thin laminates containing unidirectional filaments.The stiffness and thus the spring constant of such composite laminatecantilever springs is greatly dependent upon the tensile strength, andthe in plane interlaminar shear strength of the matrix material whichbonds together the individual laminate plies. For this reason thetensile strength and the spring constant of prior art composite laminatecantilever springs is matrix dependent since such springs can notefficiently utilize ths stiffness and strength of the filamentreinforcements comprising the material from which they are constructed.

I have discovered that when cords of sinusoidally twinedmatrix-impregnated strands of continuous filaments are arranged inparallel fashion on a forming surface and individually tensioned priorto being shaped or formed, a unitary ply of composite material isproduced from which stiff high performance composite cantilever springscan be made. Such composite springs have been found to exhibit asubstantially higher spring constant and stiffness than prior artcomposite multiple laminate springs of identical thickness andconfiguration.

I have further discovered that an array of independent compositecantilever spring members with predictable stiffness can be producedwhen a single ply of twined longitudinal filament strands is impregnatedwith a hardenable liquid matrix and formed into a tubular compositestructure having a polygonal cross section that is slotted at leastpartially along the vertices of the tubular polygon in a directionparallel to the tubular axis to provide a straight hinge line for eachspring member.

Prior art methods for making composite tubular structures comprisingtensioned longitudinal filament reinforcements generally employ asequence of overlapping laminates where each laminate comprises a singlethickness of filament strands aligned parallel to each other. Suchmethods are time consuming, complicated and expensive when used toconstruct composite tubular structures requiring a longitudinal laminateply wall thickness greater than that attainable with a single filamentstrand. The present invention teaches a method to construct tubularcomposite structures having a single ply wall thickness governed by thecross section area of a twine of strands.

Prior art composite multiple ply structures which resist hightemperature and which will not burn are generally made with a singleliquid matrix that possesses the desired heat resistance and non-burningproperties. Prior art methods employed to fabricate such non-burninghigh temperature composites generally require the use of non-combustibleadditives which tend to lower the viscosity of the liquid matrix andthereby inhibit a thorough impregnation of the filament reinforcementstrands and thus reduce the composite material strength. To overcomethis problem prior art non-burning composites commonly comprise a liquidpolymer matrix blended with liquid halogen-containing fire-retardantadditives. Such composites, when subjected to fire or extreme heat notonly decompose and lose strength but release deadly toxichalogen-containing gases that not only impede fire fighting operationsbut may cause fatalities among persons exposed to such fire-producedgases.

I have discovered a non-combustible liquid matrix material that, whilein a liquid uncured state, is compatible with most conventional uncuredcombustible thermosetting polymer materials. A composite structure whichpossesses greater resistance to degradation from fire or heat can befabricated when filament strand reinforcements impregnated with acombustible thermosetting resin are twined or otherwise intimatelycombined with other filament strand reinforcements that are impregnatedwith the compatible non-combustible liquid matrix.

Prior art composite couplings such as described in U.S. Pat. No.4,385,644 employ non-bevelled composite flanges comprising alongitudinal filament ply sandwiched between two annular composite ringscontaining circumferentially oriented continuous filament strands one ofwhich rings serves as the flange load face. Composite coupling flangeshaving this construction are unable to resist tensile strength couplingloads that exceed the interlaminar shear strength of the resin matrixbonding the sandwiched plies together. Such non-bevelled inwardly facingcomposite ring coupling flanges are further unable to act as flangedcomposite spring members that flex and thereby assist coupling assemblyas well as provide the longitudinal assembly force required tosufficiently compress an elastomeric gasket to accomplish a face sealbetween abutting pipe joint ends. When experiencing tensile end loadssuch prior art segmented composite couplings do not act to secure andlock an encircling composite sleeve structure so as to preventdisassembly when subjected to longitudinal stress.

Prior art annular composite sleeves used to assemble and encirclesegmented composite coupling structures are not divided to enable easiercoupling assembly as well as impose a compressive radial force upon onlythe outer faces of each coupling flange.

Prior art tubular composite laminates are generally single wallstructures which are stiffened by use of sandwiched sand-resin mixturesor structural foam. Such structures are poorly suited to serve as beamsor structural members subjected to bending stresses since they dependupon the interlaminar shear characteristics of the matrix material usedto bond the laminates to the foam or filler material sandwiched betweenthem. Such prior art tubular composite structures poorly resistdelamination between inner and outer walls due to thermal stresses whichserve to change the lengths of the inner wall and outer walls.

The following summarize the objectives of this invention to overcome thelimitations of prior art composite coupling structures:

(a) To provide a superior coupling to connect composite panels andtubular structures.

(b) To provide a composite spigot and socket coupling structure that isan integral structural constituent of composite pressure pipe.

(c) To provide a composite coupling structure able to easily connecthigh pressure pipe.

(d) To provide a composite mechanical coupling that is able to make andmaintain a compression pressure seal between connected pipe joint faces.

(e) To provide a high temperature composite material that resistsdeterioration and loss of strength when exposed to fire.

(f) To provide composite beam, truss and panel structures that can beeasily joined or disconnected.

(g) To provide a composite coupling structure that resists disassemblywhen subjected to tensile end loads.

(h) To provide apparatus and methods for making a wide range ofcomposite coupling structures having predictable characteristics ofstrength and sealing capability.

SUMMARY OF THE INVENTION

One aspect of this invention is directed to a method for forming acomposite twine structure, having a longitudinal axis, comprising thesteps of impregnating at least two filament strands, each composed of amultiple of individual filament reinforcements, with a first hardenableliquid adhesive constituent, twining together the impregnated filamentstrands in the direction of the axis so that the impregnated filamentstrands each exhibit a helical frequency and configuration defined by amultiple of revolutions of the strands with each of the strands havinghelixes that are spaced relative to the helixes of the other strands inthe direction of the axis, and curing the liquid adhesive to form ahardenable bonding matrix maintaining the filament strands as thecomposite twine structure.

In another aspect of this invention, a method for making a twine cordcomprises the steps of pulling a multiple of continuous dry firstfilament strands from a multiple of first strand supply packages,twisting loosely together the first filament strands to form a firsttwine of unidirectional helically configured filament strands,impregnating the first twine filament strands with a surplus ofhardenable liquid adhesive means to form a wetted first twine, pulling amultiple of continuous dry second filament strands from a multiple ofsecond strand supply packages, twisting loosely together the secondfilament strands to form a second twine of unidirectional helicallyconfigured dry filament strands, twisting loosely and simultaneouslycompressing the first and second twines together to form a twine cord,impregnating by capillarity the dry second filament strands with thesurplus of the hardenable liquid adhesive means impregnating the wettedfirst twine, and squeezing the twine cord to remove the residual surplusliquid adhesive means therefrom.

In still another aspect of this invention, a method for making acomposite structure on a longitudinal axis thereof comprises the stepsof twisting strands containing continuous filament reinforcementstogether to form a first ply twine impregnating the first ply twine witha hardenable adhesive means, securing a first end of the first ply twineto a first extremity of a forming surface, disposing a first twinelength of the first ply twine to extend in the direction of said axis,suspending the first twine length across at least one flange formingcavity of the forming surface, securing a first loop end of the firstply twine to a second extremity of the forming surface, disposing asecond twine length of the first ply twine adjacent to the first twinelength, securing a second loop end of the first ply twine to the firstextremity, repeating the steps of disposing the first ply twine as asequence of the adjacent twine lengths formed from the adjacentplacement of a multiple of the longitudinal looped twines having saidloop ends secured to opposite extremities of said forming surface,securing a second end of the first ply twine to the first extremity ofthe forming surface, twisting strands containing continuous filamentreinforcements together to form a second ply twine of dry strands,impregnating the second ply twine with a hardenable adhesive means,applying the second ply twine transversely across the multiple first plytwine to impose a substantially uniform load thereon and provide a firstply hinge line edge, deflecting the first ply twine into the flangeforming cavity by the second ply twine, moving the loop ends of thefirst ply twine secured to the second extremity of the forming surfacetoward the flange forming cavity, and placing the second ply twine uponthe first ply twine to tension and straighten the first ply twine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a single twine of helically configuredcontinuous filament strands impregnated with a hardenable liquid matrix.

FIG. 1B is similar to FIG. 1A except the helically twined strands areshown configured about a central twine core.

FIG. 2 is similar to the view of FIG. 1 but illustrates the parametersof a twine diameter and helical coil frequency of individual strands.

FIG. 3A is an exploded perspective view of a segmented couplingstructure assembly used to join externally flanged pipe joints.

FIG. 3B is similar to view of FIG. 3A except flanges are slotted.

FIG. 4 is a perspective view of the socket end of a tubular spring-lockcoupling structure.

FIG. 5 is a perspective view of the flanged spigot end of a tubularspring-lock coupling structure.

FIG. 6 is a perspective view illustrating partial insertion of a spigotend structure into the socket end of a mating spring-lock couplingstructure.

FIG. 7 is a perspective view of a tubular spring-lock coupling structureconnected to a mating spigot-end structure.

FIG. 8 is a half sectional view of a spring-lock coupling with twosocket ends connecting pipe joint ends.

FIG. 9 is a perspective view of a double-socket spring-lock pipecoupling structure connected to a spigot-ended pipe fitting.

FIG. 10 is a half sectional perspective view of a structural sealingassembly between a tubular spigot end structure and the socket end of adouble wall spring lock coupling structure.

FIG. 11 is a partially sectioned side elevation view of a double-sockettorque-resisting spring lock coupling structure.

FIG. 12 is a perspective view of the torque-resisting coupling structureof FIG. 11 connecting a powered shaft to a driven shaft.

FIG. 13 is a perspective view of a double-socket spring lock couplingstructure connected to a joint structure having a multiple of matingspigot ends.

FIG. 14 is a perspective view of a structural truss made from anassembly of socket-ended spring lock coupling structures andspigot-ended joints.

FIG. 15 is a partially sectioned side elevational view of a structuralassembly made from a double-socket spring lock coupling structureconnected to joint structures having a multiple of spigot ends.

FIG. 16 is a partially-sectioned perspective view of a flat ribbeddouble wall spring lock coupling structure.

FIG. 17 is a similar view of a single spigot and socket element of theribbed double wall panel coupling structure shown in FIG. 16.

FIG. 18 is a sectional perspective view of one side of a flat springlock coupling structure.

FIG. 19 is a similar view of an assembly of two double-sided flat springlock coupling structures.

FIG. 20 is a sectional perspective view of a channel shaped spring lockcoupling structure with double-sided socket end.

FIG. 21 is a similar view of an I-beam shaped spring lock couplingstructure with a double-sided socket end.

FIG. 22 is a partially fragmented sectional perspective view of anassembly of square tube spring lock coupling structures withdouble-sided socket ends.

FIG. 23 is a perspective view of a rotatable form support mandrelapparatus used to make the illustrated segmented composite couplingstructures thereon.

FIG. 24 is a perspective view of a pwered mandrel carriage transverseapparatus.

FIG. 25 is a perspective view of a powered mandrel carriage apparatus.

FIG. 26 is an exploded isometric view illustrating a reciptrocatingtwine-loop forming apparatus and a support structure thereof.

FIG. 27 is a schematic perspective view illustrating the method andapparatus for making, impregnating, placing and forming longitudinallyoriented twines including coupler forming apparatus.

FIG. 28 is a partially sectioned side elevation view of apparatusbeginning the first cycle of a method to position loops oflongitudinally oriented twines upon coupler forming apparatus.

FIG. 29 is a view similar to FIG. 28 but showing the apparatuscompleting the first cycle of operation.

FIG. 30 is a view similar to FIG. 28 but showing the apparatus beginningthe return cycle of operation.

FIG. 31 is a view similar to FIG. 28 but showing the apparatuscompleting the return cycle of operation.

FIG. 32 is a half sectional perspective view of a segmented partiallycompleted coupling structure made upon coupler forming apparatus.

FIG. 33 is a similar view of a pipe plug retaining type couplingstructure made upon coupler forming apparatus.

FIG. 34 is a similar view exhibiting the operations depicted in FIGS.26, 27, 28 and 29 but also showing power drive and cycle controlapparatus.

FIG. 35 is a half sectioned side elevation and schematic view ofcoupling assembly apparatus used to insert a spigot ended structure intothe socket end of a spring lock coupling structure.

FIG. 36 is a view similar to FIG. 35 but exhibiting a following step ina spring lock coupling assembly operation.

FIG. 37 is a view similar to FIG. 35 but exhibiting removal of theapparatus upon completion of the coupling assembly.

FIG. 38 is a view similar to FIG. 35 but showing coupler disconnectingapparatus in position to separate coupled pipe ends.

FIG. 39 is a view similar to FIG. 38 but showing the apparatus as it isused to perform the first step in separating coupled pipe.

FIG. 40 is a view similar to FIG. 38 but showing the apparatus as it isused to perform a following step in separating coupled pipe.

FIG. 41 is a view similar to FIG. 38 but showing the apparatus as itcompletes a method of separating coupled pipe.

FIG. 42 is a view similar to FIG. 38 showing the removable anchor ringapparatus which may be used to assemble or disconnect the illustratedcoupling structures of this invention.

FIG. 43 is a perspective view depicting twined strands of filamentreinforcement bonded to form a first ply and configured as the flangedspring member of a spring lock coupling structure.

FIG. 44 is a fragmentary perspective view which schematicallyillustrates a method and apparatus for making, impregnating, flatteningand placing circumferentially oriented twines.

FIG. 45 is a partially sectioned perspective view of the polygon sectionsocket end of a spring lock pressure coupling.

FIG. 46 is a cross sectioned side elevational perspective view of aspring lock coupler having a socket end similar to that of FIG. 45 butshowing the coupling structure with a mating flanged spigot end.

FIG. 47 is an enlarged fragmentary sectioned perspective view of amating spigot end partially inserted into the sealing socket end of aspring lock pressure coupling.

FIG. 48 is a half section side elevational view of a ribbed double wallspring lock pressure coupling having outwardly flanged segmented springmembers which provide the flanged spigot which couples with the oppositesocket end of an identical double wall spring lock pressure coupling.

FIG. 49 is a view similar to FIG. 48 illustrating a seal-containingspring lock pressure coupling connected to the spigot end of a matingpipe or fitting.

FIG. 50 is a fragmentary half section side elevational view of flangedpipe ends connected by two semi-circular coupling structures secured bytwo cylindrical composite retaining sleeve members.

FIG. 51 is a view similar to FIG. 50 but showing the segmented couplingassembly of FIG. 50 connecting socket and spigot pipe joint ends whichare able to maintain a pressure seal while accomodating an elongation ofthe coupling-structure.

FIG. 52 is a view similar to FIG. 50 but showing the segmented couplingconnecting socket end pipe joints sealed by two compressible seals and aseparable spigot ring.

FIG. 53 is a view similar to FIG. 50 but showing a segmented couplingwhich accomodates an intermediate socket ring adapter to enable sealingbetween identical spigot end pipe joints.

FIG. 54 is a view similar to FIG. 50 but showing a segmented couplingwhich accomodates an intermediate spigot ring adapter to enable sealingbetween identical socket end pipe joints.

FIG. 55 is a cross sectional dimensional view of an extremity of acomposite coupling structure body member showing the first ply extremityconfigured as the flange member of a composite cantilever spring whichdeflects about a straight hinge line.

FIG. 56 is a cross-sectional dimensional view of an extremity of asegmented composite coupling structure body member showing the couplingfirst ply extremity configured as the flange member of a cantileverspring which deflects about a curved hinge line when compressed by anencircling retaining sleeve.

FIG. 57 is an enlarged cross-sectional dimensional view of the first plyspring member of a segmented coupling structure that shows thedeflection range of the cantilever composite spring member about itshinge line.

FIG. 58 is an enlarged cross-sectional dimensional view of the first plyspring member extremity of a spring lock coupling showing it configuredto provide the load face of an integral flange member.

FIG. 59 is a fragmentary half-section side elevational dimensional viewof a segmented pipe joint coupling structure showing the flanged springdeflection about a curved hinge line when deflected by an encirclingretaining sleeve containment structure.

FIG. 60 is a fragmentary perspective view of a segmented coupling firstply structure configured to serve as a cantilever spring member as wellas the load face and outer structure of the coupling flange member.

FIG. 61 is a similar view showing the coupler second ply structure withrespect to the first ply coupling structure shown in FIG. 60.

FIG. 62 is a cross sectional dimensional view depicting the principalconstituents and dimensions of a two ply composite spring lock couplingstructure made in accordance with the teaching of this invention.

FIG. 63 is similar to FIG. 62 but showing a tapered first ply bodymember and the location of principal load resisting forces acting upon acoupling structure.

FIG. 64 is similar to FIG. 63 but showing the coupling body membercomprising a third ply structure.

FIG. 65 is an end view of a cross section between the flange and bodymembers of the spring lock coupling structure depicted in FIGS. 4, 45and 46 showing the polygonal arrangement of the straight hinge linesabout which the flat cantilever spring members deflect.

FIG. 66 is a cross sectional side elevation dimensional view of thecoupling structure shown in FIGS. 45 and 46 but showing the principalload vectors and dimensions associated with the behavior of a singleflanged cantilever spring member.

FIG. 67 is an idealized perspective view showing only the first plyextremity of the cylindrical body member of a spring lock couplingstructure so as to display the parallel alignment of the twined strandcords which are configured to provide the flanged cantilever springmember which deflects about a straight hinge line.

FIG. 68 is an idealized perspective view showing the position of body,spring and flange members of a spring lock coupling structure whendeflected about the straight spring hinge line.

FIG. 69 is a half section side elevational fragmentary view showing thecomposite ply configurations characterizing the body extremities of twounconnected mating spring lock pressure coupling structures and loadvectors associated with coupling assembly.

FIG. 70 is a view similar to FIG. 69 showing dimensional callouts of acoupling body spigot and socket end construction.

FIG. 71 is a view similar to FIG. 69 showing the coupling assembly forcechanges with the spigot flange insertion face angle.

FIG. 72 is a partially fragmented perspective view of a typicalpressure-resistant cylindrical body member of a spigot-ended spring-lockcoupling structure.

FIG. 72A is an enlarged view of the portion of the body member, takenwithin circle 72A--72A in FIG. 72.

FIG. 73 is a fragmentary perspective view of a rectangular spring-lockcoupling used as a clip.

FIG. 74 is a side elevation cross section view of the socket end of aspring-lock coupling structure having a solid body member cross sectionin the shape of a regular polygon.

FIGS. 74A and 74B are left and right end views of the coupling structureshown in FIG. 74, respectively.

FIG. 75 is a side elevation cross section view of the flanged spigot endof an elongated solid coupling structure body member.

FIG. 76 is a side elevation cross section view showing the connection ofthe spigot and socket ends of a coupling structure having an elongatedsolid body member.

FIG. 77 is a fragmentary partial cross section of a spring lock couplingstructure configuration having a ring-shaped body member and an annularpolygonal array of flanged composite cantilever springs retained by apolygonal-shaped lock sleeve to provide a coupling socket end whichengages the spigot end of a composite cable structure.

FIG. 78 is an exploded perspective view of a movable spring-lockcoupling structure with a cylindrical retaining sleeve member used tojoin externally flanged pipe butt joints.

FIG. 79 is a fragmentary sectioned perspective view of a movablespring-lock coupling structure in the retracted position.

FIG. 80 is a view similar to FIG. 79 illustrating the extended positionof the movable spring-lock coupling structure as it initiates aconnection between flanged-joint pipe ends.

FIG. 81 is a view similar to FIG. 80 illustrating the polygonal array offlanged cantilever composite springs being deflected as the movablespring-lock coupling structure is in process of connecting flanged buttjoint pipe ends.

FIG. 82 is a view similar to FIG. 81 illustrating a movable spring-lockcoupling and retaining sleeve structure connecting identical flangedjoint pipe ends having a face seal capability.

EXAMPLE I

The preferred embodiment of the present invention involves making acomposite structure from at least one twine comprising a multiple ofunidirectional helically configured strands 4 which contain continuousfilament reinforcements 5. FIG. 1A illustrates in enlarged perspectiveview a single twine 7 containing a multiple of helically configuredstrands 4 which contain continuous filament reinforcements 5 impregnatedwith a hardenable liquid matrix 6. FIG. 1B is a similar view butillustrating a twine construction configured about a twine core member70 around which twined strands 4 are placed. FIG. 2 is intended to showthat a side projection of any single helically configured strand 4contained in a twine of strands employed in the present inventionexhibits an approximate sinusoidal orientation when viewed on animaginary plane parallel to the direction of the twine orientation. Thegeneric term which most accurately describes composite ply structuresmade from twined strands is "Unidirected Sinusoidal Composite".

A single ply of parallel twines which comprise unidirected helicallyconfigured strands 4 containing numerous continuous filamentreinforcements 5 provides greater flexural strength than a prior artcomposite ply of the same shape and section made from two or more thinlaminates comprising unidirectional parallel untwisted strands offilament reinforcement. This is because the bending and flexuralstrength of prior art laminate plies is limited by the tensile and shearstrength of the relatively weak matrix material used to bond togetherthe individual layers. This invention teaches that twine-containingplies possess a stiffness and bending strength that is not governed bymatrix properties but by the transverse shear strength and tensilestrength provided by the material composition and helical configurationof the filament reinforcements comprising each twine.

Prior art unidirectional laminate plies are constructed from parallelcollimated strands of filament reinforcement. Such plies when flexed orbent as spring members are limited in flexural strength by the tensileand shear strength of the matrix material which impregnates the filamentreinforcements and bonds together the individual lamina or layers ofcollimated strands. Prior art composite spring structures are thus"matrix dependent" structures.

The helically configured arrangement of filament reinforcementscomprising a composite ply of unidirectional twines of continuousfilament strands overcomes prior art matrix-dependent limitations byincreasing the stiffness and flexural strength of a composite ply havinga given thickness. This improvement results from the contribution of thetransverse shear strength of the filaments to overcome matrix strengthlimitations and better resist the shear stresses produced by bendingforces applied to the composite ply. The transverse shear value, asdetermined by the ASTM D732-78 test method, is as much as seven timesgreater than the matrix interlaminar shear and tensile strength used tobond together a multiplelayer ply of laminates made from parallelunidirectional filament strands containing collimated filamentreinforcements.

The term "sinusoidal twined strand frequency" is introduced to definethe orientation of filament reinforcements contained in the twines ofcontinuous filament strands. The more turns or revolutions a strandmakes per unit length of a twine of helically configured strands thehigher the "sinusoidal twined strand frequency" and the greater thestiffness provided to a twine ply of given thickness. The transversetensile strength of the composite ply material in a directionperpendicular to the general orientation of the twine of strandsincreases with the "sinusoidal twined strand frequency" to a valueapproaching the transverse shear strength of a unidirected compositelaminate ply made from straight and parallel filament reinforcementssimilar to those used in the twined strand composite ply. The"sinusoidal twined strand frequency" shall hereafter in this patentspecification be referred to as the "Twined Strand Frequency" and shallbe designated by the symbol "F_(tw) " in mathematical formulas used inits determination. The "Twined Strand Frequency" is measured in "cyclesper meter" which is meant to refer to the number of complete helicalturns made by a single strand in a unit length of twine. FIGS. 27 and 44schematically illustrate apparatus which may be used to make andimpregnate dry twines 7A of helically configured strands 4. The "TwinedStrand Frequency", "F_(tw) ", is increased by increasing the number ofuntwined strands of continuous filament reinforcement 4A fed from strandpackages 50 into the twine forming funnel tube apparatus 53. An untwinedstrand 4A of E glass filament roving having a yield of 500 meters perkilogram contains 3200 individual filaments 5, each filament having adiameter of 20 microns. This type of roving strand is 0.3 mm thick and 3mm wide and produces a helical configuration to the strand when pulledaxially from the center or outside of a cylindrical strand-wound package50 in a direction parallel to the package axis 50A. A typical 18 kgcenter pull cylindrical roving package is 250 mm in diameter, 250 mmhigh and provides a "Center Pull Helical Frecuency" (designated by thesymbol "F_(cp) ") of 4.4 cycles per meter which results from the strandmaking one helical twist per 227 mm of strand length as it is pulledaxially from the strand package 50. The "TWINED STRAND FREQUENCY","F_(tw) ", can be calculated from the formula: F_(tw) =N (F_(cp)), where"N" is the number of strands contained in the twine. For example, atwine containing 9 strands having a CENTER PULL FREQUENCY, "F_(cp) "equal to 4.4 cycles per meter has a "Twined Strand Frequency" equal to40 cycles per meter. The " Twined Strand Frequency" is useful incalculating the bending strength of a twine ply: the higher the TwinedStrand Frequency the greater the twine ply bending strength for a giventype of strand of filament reinforcements. The empriical formula fromwhich the minimum thickness, "T", of a composite ply made from a singletwine can be determined is: T=t_(s) (N)^(1/2), where "t_(s) " is thethickness of an individual strand of filament reinforcements and "N" isthe number of strands contained in the twine 7.

The highest stress region of a cantilever beam member subjected tobending is near the outer surface where the bending moment is greatest.These stresses are compression stresses on the concave surface portionof a flexed member and tensile stresses on the convex surface portion.Unfortunately prior art laminate plies used to make cantilever beammembers are matrix dependent and for this reason delaminate when theinner ply tensile strength of the matrix material is reached. Thisoccurs near the center of the cantilever beam where the transition fromtensile to compressive stress occurs. Thus, the strength of thecomposite filament reinforcement material cannot be efficiently put touse. The helical arrangement of filament reinforcements comprisingtwines used to make such cantilever beams provides a way to increase thestiffness and bending strength of composite cantilever beams.

The standard test method for determining flexural properties ofcomposite materials is the ASTM D790 test method. The flexural strengthfrom this test method is equal to the maximum stress in the outer plymaterial at the moment of break. This strength is governed by the ASTMflexural test formula: S=3 PL/2Bd² where "S" is the stress in outerfibers at midspan, measured in Megapascals (MPa), "P" is the load at agiven point on the load delection curve, measured in Newtons (N), "L" isthe length of the support span measured in millimeters (mm) and "d" isthe depth of the beam tested (mm). To compare the increased flexuralstrength attainable from the helical arrangement of filamentreinforcements contained in a composite twine ply, flexural tests weremade of two composite beams. One beam was made from a conventional priorart type ten ply laminate having all unidirected glass filamentreinforcements oriented in the direction of the span. A thermosettingpolyester resin was used as the matrix material. A second beam was madefrom a single twine of 32 strands of glass roving having a yield of 500m/kg and a center pull frequency "F_(cp) " of 4.4 cycles/meter. Thetwine composite beam was characterized as being made from a twine havinga "Twined Strand Frequency", "F_(tw) " equal to N×F_(cp) =32×4.4=141cycles/meter. Each beam had a thickness, "d", equal to 5 mm, a width,"b", equal to 10 mm, and a length of 100 mm. A support span, "L" of 80mm was used with each beam specimen supported on 15 mm diameter polishedsteel supports and a loading nose radius of 20 mm. ASTM D790 Method Iwas employed using a cross head motion of 2.0 mm/min.

The conventional prior art type laminate beam failed at a load of 37.1KN (8330 lb) and exhibited a stress of 17.8 MPa (2580 PSI) at failurewhich occurred as a delamination between two inner plies.

The beam made from a twine of 32 strands resisted a load nearly fourtimes greater than that resisted by the prior art type beam. A slightfracture was produced at a load of 138 KN (31,000 lb) on the concaveside of the twine beam. The flexural stress when this occurred was 66MPa (9604 PSI). The twine beam remained intact however and was capableof resisting additional load.

Each ply comprising the composite coupling structures of the presentinvention is made from one or more of the "twines", previously describedand illustrated in FIGS. 1A and 1B., which are generally orientedapproximately parallel and adjacent to each other.

Table I illustrates the fact that the average strength of a continuousfilament reinforcement 5 decreases as it is collected first into asingle strand 4A and subsequently as a twine of helically configuredstrands 7. Table I further discloses the recommended design values of acomposite ply of longitudinally oriented twines, termed "LONGOS", and acomposite ply of circumferentially oriented twines, termed "CIRCS", suchas those used in preferred embodiments of the present invention.

                                      TABLE I                                     __________________________________________________________________________    PROPERTIES OF GLASS FILAMENTS, STRANDS AND COMPOSITE TWINES                                   TENSILE STRENGTH                                                                          TENSILE    STRAIN                                                                             AVG. DENSITY                                                                           SINGLE STRAND                            (σ)   MODULUS (E)                                                                              (ε)                                                                        (ρ)  CROSS SECTION                            GN/m.sup.2                                                                          PSI   GN/m.sup.2                                                                         PSI   %    gm/cc                                                                             #/cu in                                                                            mm.sup.2                                                                           in.sup.2            __________________________________________________________________________    SINGLE FILAMENT 1.71  247,500                                                                             72.4 10.5 × 10.sup.6                                                               2.4  2.52                                                                              0.091                                                                              2.7                                                                                4.25 ×        PROPERTIES OF                                        10.sup.-4                                                                          10.sup.31 7         E GLASS (20 MICRON                                                            DIAMETER)                                                                     SINGLE STRAND OF                                                                              1.28  185,000                                                                             53.46                                                                              7.74 × 10.sup.6                                                               2.4  2.52                                                                              0.091                                                                               0.877                                                                              .00136             3200 DRY                                                                      GLASS FILAMENTS                                                               SINGLE STRAND OF                                                                              1.15  167,000                                                                             29.02                                                                              4.21 × 10.sup.6                                                               4.0  1.91                                                                              0.069                                                                              1.61 .0025               3200 MATRIX                                                                   IMPREGNATED                                                                   GLASS FILAMENTS                                                               SINGLE TWINE OF 20                                                                            0.86  125,200                                                                             24.2 3.51 × 10.sup.6                                                               3.6  1.77                                                                              0.064                                                                              1.94 .0030               HELICALLY CONFIGURED                                                          STRANDS (3200 FILA-                                                           MENTS PER STRAND)                                                             DESIGN VALUES OF A                                                                            0.12   18,000                                                                             24.2 3.51 × 10.sup.6                                                               0.51 1.77                                                                              0.064                                                                              1.94 .0030               COMPOSITE CIRC PLY                                                            MADE FROM                                                                     CIRCUMFERENTIAL                                                               TWINES                                                                        DESIGN VALUES OF A                                                                            0.10   15,000                                                                             24.2 3.51 × 10.sup.6                                                               0.43 1.77                                                                              0.064                                                                              1.94 .0030               COMPOSITE LONGO PLY                                                           MADE FROM PARALLEL                                                            LONGITUDINAL                                                                  TWINES                                                                        __________________________________________________________________________

EXAMPLE II

Another preferred embodiment of this invention is to make a compositestructure from at least one ply of parallel twines.

Table II presents the properties of a unidirected composite ply madefrom parallel twine of helically configured roving strands having ayield ranging from 200 to 500 m/kg and containing continuous filamentsof E-glass impregnated with a thermosetting polyester resin matrix. Asmay be noted from Table II the transverse shear strength of a twine plycomposite material is approximately a fourth the maximum tensilestrength. The design practice employed in preferred embodiments of thepresent invention is to use approximately 50% of the twine ply maximumtransverse shear strength and approximately 20% of the twine ply maximumtensile strength as the allowable design strength of the composite twineply material. The composite twine material properties presented in TableII are those of twine ply composite material with a filamentreinforcement volume of approximately 46% and a "TWINED STRANDFREQUENCY" in the range of 10 to 100 cycles/meter.

Table III presents the strength characteristics and design parameters oftwines employed in making a first ply of a composite structurerepresenting a preferred embodiment of the present invention. The firstply of a multiple ply embodiment is made from a series of loops of twinecords 7B placed parallel and adjacent to each other and orientedlongitudinally upon a forming mandrel having opposing rows of twine loopanchor pins. The spacing of the loop end anchor pins govern theselection of the number of strands per twine cord as well as control thefinished ply thickness of the pair of looped twine cords secured by andplaced between adjacent anchor pins.

                                      TABLE II                                    __________________________________________________________________________     PROPERTIES OF A SINGLE COMPOSITE PLY OF PARALLEL UNIDIRECTED                 __________________________________________________________________________    TWINES                                                                        LONGITUDINAL TENSILE STRENGTH (ASTM D638)                                                                     0.86 GN/m.sup.2                                                                          125,200 PSI                        LONGITUDINAL TENSILE MODULUS (ASTM D638)                                                                      24.2 GN/m.sup.2                                                                          3.51 × 10.sup.6 PSI          LONGITUDINAL TENSILE STRAIN (ASTM D638)                                                                       3.6%       0.036 IN/IN                        LONGITUDINAL COMPRESSIVE STRENGTH (ASTM D695)                                                                 0.345 GN/m.sup.2                                                                         50,000 PSI                         LONGITUDINAL COMPRESSIVE MODULUS (ASTM D695)                                                                  24.2 GN/m.sup.2                                                                          3.51 × 10.sup.6 PSI          LONGITUDINAL COMPRESSIVE STRAIN (ASTM D695)                                                                   1.4%       0.014 IN/IN                        TRANSVERSE TENSILE STRENGTH (ASTM D638)                                                                       0.103 GN/m.sup.2                                                                         15,000 PSI                         TRANSVERSE TENSILE MODULUS (ASTM D638)                                                                        10.3 GN/m.sup.2                                                                          1.5 × 10.sup.6 PSI           TRANSVERSE TENSILE STRAIN (ASTM D638)                                                                         1.0%       0.01 IN/IN                         TRANSVERSE COMPRESSIVE STRENGTH (ASTM D695)                                                                   0.138 GN/m.sup.2                                                                         20,000 PSI                         TRANSVERSE COMPRESSIVE MODULUS (ASTM D695)                                                                    8.27 GN/m.sup.2                                                                          1.2 × 10.sup.6 PSI           TRANSVERSE COMPRESSIVE STRAIN (ASTM D695)                                                                     1.6%       0.0166 IN/IN                       TRANSVERSE SHEAR STRENGTH (ASTM D732)                                                                         0.227 GN/m.sup.2                                                                         33,000 PSI                         TRANSVERSE SHEAR MODULUS (ASTM D747)                                                                          24.2 GN/m.sup.2                                                                          3.51 × 10.sup.6 PSI          TRANSVERSE SHEAR STRAIN (ASTM D747)                                                                           0.9%       0.009 IN/IN                        MATRIX TENSILE STRENGTH (ASTM D638)                                                                           0.09 GN/m.sup.2                                                                          13,000 PSI                         MATRIX TENSILE MODULUS (ASTM D638)                                                                            2.41 GN/m.sup. 2                                                                         0.35 × 10.sup.6 PSI          LONGITUDINAL POISSON'S RATIO (ASTM D638)                                                                      0.25       0.25                               LONGITUDINAL COEF. OF LINEAR    11 × 10.sup.-6 cm/cm/°C.                                                    11 × 10.sup.-6                                                          IN/IN/°C.                   THERMAL EXPANSION (ASTM D696)                                                 TRANSVERSE COEF. OF LINEAR      55 × 10.sup.-6 cm/cm/°C.                                                    55 × 10.sup.-6                                                          IN/IN/°C.                   THERMAL EXPANSION (ASTM D696)                                                 __________________________________________________________________________     NOTES:                                                                        1. EACH TWINED STRAND EXHIBITS A YIELD RANGING FROM 200 TO 500 M/KG AND A     "CENTER PULL FREQUENCY" RANGING FROM 4 TO 5 CYCLES PER METER.                 2. TWINES COMPRISE 3 TO 25 STRANDS OF HELICALLY CONFIGURED EGLASS FILAMEN     REINFORCEMENTS IMPREGNATED WITH THERMOSETTING POLYESTER RESIN MATRIX, A       FILAMENT VOLUME FRACTION = 46%, AND A "TWINED STRAND FREQUENCY" FROM 10 T     100 CYCLES PER METER.                                                    

                                      TABLE III                                   __________________________________________________________________________    TWINE PLY DESIGN PARAMETERS                                                          TWINE PLY                                                                            TWINE PLY   TWINE PLY         FLATTENED                         NUMBER DESIGN C.S.A.(SQ IN)                                                                             AVG. DIA.                                                                            PIN SPACING                                                                              TWINE PLY                         STRANDS                                                                              STRENGTH                                                                             1 mm.sup.2 = .00155 SQ IN                                                                 mm (IN)                                                                              (2 CORDS PER PIN)                                                                        THICKNESS                         PER TWINE                                                                            kN (lb)                                                                              mm.sup.2 (IN.sup.2)                                                                       .0394 mm/IN                                                                          mm (IN)    mm (IN)                           __________________________________________________________________________     5     1 (225)                                                                               8 (.0125)   3.2 (.13)                                                                           16 (.63)    1.0 (.039)                       10     2 (450)                                                                              16 (.025)    4.5 (.18)                                                                           16 (.63)   2.0 (.08)                         15     3 (675)                                                                               24 (.0375)  5.6 (.22)                                                                           16 (.63)   3.0 (.12)                         20     4 (900)                                                                              32 (.050)    6.4 (.25)                                                                           16 (.63)   4.0 (.16)                         25      5 (1125)                                                                            40 (.062)    7.1 (.28)                                                                           16 (.63)   5.0 (.20)                         30      6 (1350)                                                                            48 (.075)    7.8 (.31)                                                                           16 (.63)   6.0 (.24)                         40      8 (1800)                                                                            65 (.100)    9.1 (.36)                                                                           18 (.72)   7.0 (.28)                         50     10 (2250)                                                                            81 (.125)   10.1 (.40)                                                                           20 (.80)   7.9 (.31)                         60     12 (2700)                                                                            97 (.150)   11.1 (.44)                                                                           22 (.88)   8.6 (.34)                         75     15 (3375)                                                                            121 (.188)  12.4 (.49)                                                                           28 (1.1)   8.6 (.34)                         100    20 (4500)                                                                            161 (.250)  14.3 (.56)                                                                           35 (1.4)   9.0 (.36)                         125    25 (5625)                                                                            202 (.313)  16.0 (.63)                                                                           40 (1.6)   10.0 (.39)                        150    30 (6750)                                                                            242 (.375)  17.6 (.69)                                                                           48 (1.9)   10.0 (.39)                        200    40 (9000)                                                                            322 (.500)  20.2 (.80)                                                                           51 (2.0)   12.7 (.50)                        250     50 (11250)                                                                          403 (.625)  23.3 (.92)                                                                           51 (2.0)   15.9 (.625)                       300     60 (13500)                                                                          484 (.750)  24.8 (.98)                                                                           51 (2.0)   19.0 (.750)                       __________________________________________________________________________

EXAMPLE III

FIGS. 56 and 66 illustrate another preferred embodiment of thisinvention and exhibit how two or more plies of unidirected paralleltwines can be configured to provide flanged composite cantilever springswhich can be used in the construction of mechanical coupling structureswhich facilitate coupling operation and resist shear and tensilestresses when subjected to coupling loads. As illustrated in FIGS. 56and 66 a first ply twine 1 having a thickness "T" at the hinge line"H_(L) " is configured to provide a flanged composite cantilever spring3 . A second ply twine 2 provides a constituent of the couplingstructure flange and body member. It should be noticed that the couplingconfiguration shown in FIG. 56 is characterized by a short curvedcantilever spring member 17 which is more fully described in FIG. 57.The curved spring hinge line 11 characterizes the flanged curvedcomposite spring member of a segmented semi-circular coupling structure10. As illustrated in FIG. 56 the coupling structure 10 resists acoupling tensile load "F" only when the semi-circular flange member 14is in a deflected position 72. The coupling structure shown in FIG. 66is characterized by a long flanged flat cantilever spring member 22which resists a tensile coupling load "F" while in a non-deflectedposition 71 and which is characterized by a straight spring hinge line21 such as illustrated in FIGS. 67 and 68. FIG. 43 is a perspectiveillustration showing the configuration of the first ply constituents ofa typical flanged cantilever spring member 3 comprising the socket endof a tubular spring-lock coupling structure. The first ply 1 of theflanged spring member 3 comprises parallel longitudinal twines 9consisting of helically configured strands 4 containing helicallyconfigured filament reinforcements 5.

FIG. 66 illustrates a spring-lock coupling structure 20 comprising afirst ply flanged cantilever spring member 22 that deflects about astraight hinge line 21 at the extremity of a coupling structure bodymember 28 and serves as a deflectable socket end coupling structurecomprising a first ply flat cantilever spring member 22A and acylindrical-segment shaped flange member 23A having a flange load face23B, a flange base member 23 C, a flange heel member 23D, a flange heelcap extremity 23 E and a second ply flange member constituent 25.

EXAMPLE IV

FIGS. 4,8,9,10,11, 12, 13,19,20,21,22,45,46,47,48,49,73,74, 77,78 and 82illustrate various coupling structures that teach a preferred embodimentof this invention and which are hereafter referred to in thisspecification as the "SPRING-LOCK" type of coupling structure 20.

FIG. 4 is a perspective view of the socket end 20A of a spring-lockcoupling structure of the type illustrated in a perspective sectionalview in FIGS. 45, 46 and 47. As shown in these views the socket end ofthe spring-lock coupling structure comprises a polygonal array ofcantilever flat spring members 31 constructed as a first ply extremityof a cylindrical coupling structure body member 30. FIGS. 46 and 47illustrate the seal-containing socket-end configuration 44 of thecoupling structure third ply body member 27 as well as the spigot end ofa cylindrical body member 20BC comprising a cylindrical sealing surface40 and a cylindrical bevelled flange 100B constructed from the secondply coupling body member constitutent 26 to provide a spigot end bodymember load face 26B. As shown in FIGS. 46 and 47 a first ply structure1 comprises longitudinally oriented twines 9 configured to provide afirst ply flange member having a cylindrical interior surface 23A andillustrated in FIG. 43, a flange load face 23B, a flange base member23C, a flange heel member 23D and a flange cap 23E. The first ply 1 alsocomprises a flat cantilever spring member 22A and a cylindrical firstply body member 24A. A second ply 2 is constructed upon the first ply toprovide a second ply flange constituent 25 and a second ply body memberconstituent 26. The coupling first ply body member 24 is constructedupon a third ply body member constituent 27 which in turn is constructedupon an impermeable inner liner member 45.

FIGS. 8, 9, 11, 12, 13, 14 and 15 illustrate spring-lock couplingstructures having a pair of opposing socket ends 20A consisting of apolygonal array of flat flanged cantilever spring members 22. Thespring-lock coupler shown in cross section in FIG. 8 is used to joinflanged-end pipe 29 each of which have an annular socket-end sealingrecess 35 which accept a cylindrical spigot ring structure 37 withannular seal grooves containing a compressible seal 38. An elongatedversion of this coupling is shown in FIGS. 13, 14 and 15 as a trussmember used to connect flanged truss joints comprising spigot-endfittings 39. An elongated version of the coupling structure shown inFIG. 8 is also shown in FIGS. 11 and 12 as a torque resisting socket endcoupling structure 42 able to connect two rotating polygon-shaped spigotend members 41 having polygon-shaped spigot ends 20BP such as a poweredspigot end shaft 41A and a driven spigot shaft 41B.

FIG. 10 is an enlarged cross section showing the construction of one endof a pressure seal coupling structure such as shown in FIG. 9 used toconnect and seal spigot end pressure fittings 20BC. FIG. 10 furtherillustrates the socket end of a double wall tubular spring-lock couplingstructure 20A and its engagement with a mating spigot end compositestructure 20BC to provide a pressure seal and physical connectionbetween the two structures. The inner liner 45 provides an impermeablemembrane able to resist internal pressure. Longitudinally directedtwines 9 comprise the first ply polygon section body member 24B, thefirst ply cantilever spring member 22A and the first ply flange member23 as well as the fourth ply body member 48. Circumferentially directedtwines 8 comprise the second ply polygon section body member 26A and thesecond ply flange member 25 as well as the third ply body member 27 andthe fifth ply body member 49. Cellular material such as rigid foamcomprises the structural material 43 used to separate the inner andouter walls of the double wall spring-lock coupling structure.

FIG. 48 shows in cross section another double wall configuration of thespring-lock coupling which can be used to make flat panels as well ascomposite tubular structures able to be rapidly connected. Thespring-lock coupling configuration shown in FIG. 48 employs deflectableflanged flat cantilever composite spring members 22 as both the spigotend of a spring-lock coupling structure 20B and the socket end of aspring-lock coupling structure 20A. FIG. 48 is a cross section of adouble wall spring-lock coupling structure which has one side smooth andflush and sealed by means of a compressible elastomeric seal 38contained within a grooved portion of the third ply body member 44. Whenconstructed as a tubular body member having the cross section shown inFIG. 48 the inner cylindrical body structure comprises an impermeableliner 45, a fifth ply body member 49, a fourth ply body member 48comprising longitudinally oriented twines 9 and a third ply body member27 comprising circumferentially oriented twines 8. The outer bodystructure has a regular polygon configuration 76 and is a second plypolygonal body member 26A constructed upon a first ply polygonal bodymember 24B which is supported by polygon-shaped annular composite ribs33 made from circumferentially oriented twines that contain a twine core70.

FIG. 49 is a cross section of the mating ends of a spring-lock couplingstructure having a polygonal shaped spigot flange engaging a polygonalarray of flat cantilever socket-end spring members 31 and sealing acylindrical coupling body member 30 having mating cylindrical spigot andsocket end body member extremities which provide a pressure seal 38Abetween the two body members. FIG. 72 illustrates additionalconstruction details of pressure-containing cylindrical coupling bodymembers such as shown in FIG. 49

FIGS. 16, 17, 18, 19, 20, 21 and 22 exhibit flat panel configurations ofspring-lock coupling structures which comprise flat flanged compositespring members 22.

FIGS. 16 and 17 illustrate a ribbed hollow double-wall spring-lockcoupling structure 34 which exhibits spaced longo twine ribs 36configured to have spigot and socket end members and providing greaterrigidity and thermal insulation than a single wall structure comprisingcompacted longitudinal twines.

FIG. 18 shows the construction detail of a flat panel 32 having a lineararray of flanged spring members 3. Such panels can be made to any lengthand can be connected back-to-back as shown in FIG. 19 to provide hollowwall panels of any thickness having a flush exterior on both sides andwhich are able to be connected to other panels having similar spigot andsocket ends. Corner pieces (not shown) can also be made to enable suchpanels to provide a means to quickly make room enclosures, knock-downshipping containers and the like.

FIGS. 20, 21 and 22 are sectional perspective views of spring lock typecoupling structures which serve as structural members. The tubularrectangular beam member 73 shown in FIG. 22 exhibits a first ply flatflanged composite spring 22 member sandwiched between an outer secondply body member 26 and an inner third ply body member structure 27. Thefirst ply flange contituent 23 is configured to have a straightnon-bevelled load face 23B and to provide the entire flange bodystructure by means of the folded first ply flange body configuration 74shown in FIGS. 20, 21 and 22. Structural members which embody featuresof this invention employ at least two such flat flanged cantileverspring members which serve as a socket end which can be initiallydeflected by an assembly tool (not shown) to accept a rectangulartubular structure having a longitudinal axis at right angles to thelongitudinal orientation of the first ply twines comprising the flatcantilever spring members 22. FIG. 22 illustrates an assembly of twoparallel rectangular socket end tube structures connected by a thirdtube coupling structure having socket ends which mate with the bodydimensions of the parallel tube structures to provide a structure whichcan serve as a roof or floor support structure in environments wherecorrosion, rotting or termites would destroy other structural materials.FIG. 20 shows a socket-end configuration of a composite flanged-springcoupling structure in the shape of a structural channel 78. FIG. 21shows a socket end configuration of a composite flanged spring couplingstructure in the shape of a structural I beam 79. It should be notedthat the channel shaped coupling structure 78 can be made from alongitudinal half section of a rectangular shaped tubular couplingstructure 73 similar to that shown in FIG. 22. It should be furthernoted that the I beam structure shown in FIG. 21 can be constructed fromtwo channel members such as shown in FIG. 20.

FIG. 73 is a partially sectioned perspective view of a tubular springlock coupling structure which may be used as a retaining clip structure.This example of a coupling structure comprises a flange 23 attached to acomposite spring 22 which deflects as a cantilever beam. An opposingpair of such flanged spring members are configured to contact each otherto provide a clip opening 75 which can be structurally closed to enablethe structure to become attached to or connect another structure, suchas a cable ring. The composite structure depicted in FIG. 73 comprisesan internal rectangular tube support structure 83 which supportsparallel plies of longitudinally oriented twines 9 configured as aprimary body member 24 having at least one extremity configured toprovide mating flanged composite springs 22. The longitudinal first plytwines 9 are designed to provide the structure with longitudinalstrength and the flanged composite spring 22 with the necessary springstiffness to resist cantilever spring deflection that would exceed thedesired coupling end load resistance. The longitudinal twine plies arecontained within a composite tube comprising a single second ply ofcircumferentially wound twines 8 that provide a constituent of thecoupling structure body member 26 as well as the straight hinge line 21about which the flanged composite cantilever spring member 22 deflects.

FIGS. 74,75 and 76 depict a side elevation cross section of a compositecoupling structure used as a composite cable or composite rod structure.FIG. 74 additionally provide end views which illustrate that thecomposite rod coupling structure has a cross section in the shape of aregular polygon, such as the octagon shown, and consists of a two-plyconstruction whereby the longitudinal tensile load is resisted by aLONGO ply comprised of parallel twines oriented longitudinally 9.

FIG. 74 further illustrates that the LONGO first ply 1 is enclosed by apolygonally shaped CIRC second ply 2 comprised of circumferentiallyoriented twines 8. FIG. 74 illustrates in side elevation cross sectionthe regular polygon configuration 76 of first ply twines 1 and secondply twines 2 which are used to provide the socket end of the spring-lockcoupler polygonal section body member 24B. The socket end 20A of thecoupler body member extremity comprises a first ply cantilever springmember 22A, a first ply flange member 23 connected to the spring member22A, a first ply body member 24B connected to the spring member 22A anda second ply body member 26 enclosing the polygonal section first plybody member 24B.

FIG. 75 illustrates in side elevation cross section the configuration offirst ply twines 1 and second ply twines 2 which comprise the spigot end20B of the spring-lock coupler body member 28 serving as a rod structureand having a mating socket end structure 20A, such as shown in FIG. 74,at an opposite extremity.

FIG. 76 illustrates in side elevation cross section the connectedrelationship of a socket spring end 20A and a spigot end 20B ofspring-lock coupling structure having an elongated body member 28 whichserves as a rod or cable.

FIG. 77 shows a partially sectioned side elevation view of a compositespring-lock coupling structure having a body member structure 28 formedin the shape of a ring. The ring is constructed from a compacted rodcomprising the individual longitudinal first ply twines 9 used to makethe polygonal shaped array of flanged cantilever springs 31 whichcomprise the socket end of the coupling structure 20A. A second ply ofcircumferentially oriented twines 8 comprises the body member portionconfigured as the ring structure 77 and the second ply body member 26which provides the straight hinge lines 21 about which the flangedcantilever composite springs 22 deflect.

FIG. 77 also illustrates the location of a separable compositepolygon-shaped retaining sleeve structure 18B which is constructed fromcircumferentially oriented twines. FIG. 77 further illustrates theconnection of the socket end of the ring coupling structure 20A with thespigot end 20B of a composite rod or cable structure such as thatdepicted in FIG. 75.

FIGS. 5, 46, 47 and 48 illustrate a preferred spring-lock couplerembodiment comprising a spigot joint end composite seal surfacestructure 40 as the extremity of a cylindrical coupling body member 30.The joint end extremity of a preferred body member embodiment consistsof a cylindrical flanged spigot 20BC which mates with a seal containingsocket configuration 44 of the spring lock coupling structure to providea mechanically connected pressure seal between the spigot end and thesocket end coupling third ply body member constituent 27.

FIGS. 6, 7 and 47 depict the insertion and connected relationshipbetween the mating ends of two identical spring-lock coupling structures20 constructed as a preferred embodiment of the present invention. FIGS.47,48 and 49 illustrate preferred configurations of annular sealcontaining grooves 44 formed by the third ply body member constituent27. FIG. 47 depicts the manner by which each of the annular polygonalarray of flanged flat composite cantilever spring members 22 deflectabout their respective straight hinge lines 21 when the cylindricalflanged spigot end 20BC is inserted while axially loaded by assemblyapparatus such as shown in FIGS. 35 and 36.

FIGS. 7, and 19 depict the connected relationship between flanged spigotend joints 20B and the socket ends 20A of preferred embodiments ofspring-lock coupling structures 20 to provide a structural connectionbetween the two.

FIG. 62 illustrates a cross section of a preferred socket endconstruction of a two-ply spring-lock coupling structure 20 where thefirst ply body member 82 is a non-tapered extension of the flangedspring member 80.

FIG. 63 illustrates a two ply socket end construction of a spring-lockcoupler having a body member first ply member 82 formed as a taperedextension of the first ply spring member 80 which is configured at oneextremity as a first ply flange member 81.

FIG. 64 illustrates a cross section of a preferred socket-endconstruction of a three ply spring-lock coupling structure 20 having anexternal flange 100A and an interior spigot receiving annulus groove 35Aformed in the third ply body member extremity 27.

FIG. 65 illustrates a cross section of a tubular form of the compositespring-lock coupling structure 20 such as shown in FIG. 62 taken betweenthe coupling first ply body member 82 and the flange member 81 to showthe polygonal arrangement of the cantilever first ply spring members 80which is typical of a preferred embodiment in which the inner surface ofeach coupling spring member 80 is the side of a regular polygon and eachspring member 80 is separated at the polygon vertices and in which thespring section radius, R_(s), is the radius of a circle inscribed withinthe regular polygon and R_(B) is the radius of a circle enclosing thepolygonal array of spring members 80.

FIGS. 67 and 68 illustrate the cylindrical first ply body member 24A,the first ply flat spring member 22A and the cylindrical surface of afirst ply flange member 23A of a preferred spring-lock couplingstructure socket-end construction 20A.

FIGS. 43 and 67 illustrate the parallel arrangement of the longitudinalfirst ply twines 9 configured to provide a flanged spring member 22 of atubular spring-lock coupling socket-end construction 20A.

FIGS. 55, 56, 62, 63, 64, 65, 66, 67, 69, 70 and 71 identify theprincipal dimensions and load vectors which govern the design ofspring-lock coupling structures 20 having flanged flat cantilever springmembers 22 which resist a coupling tensile load while the spring memberis in a non-deflected position.

FIG. 55 depicts the first ply configuration of the flange constitutent23 of a spring-lock type of coupling structure which embodies certainfeatures of this invention. The flange constituent 23 is configured tohave an interior flange load face 23B which resists a compressive load,a flange base member 23C and an outer flange heel member 23D which hasan endmost part extending radially outward from a central axis 76A(designated as the line x--x in FIG. 55) to a height, "H₂ ", which is atleast equal to the height of the flange load face 23B. The flange heelmember 23D exhibits a partially circular section and the radius "R_(F) "of the curved extension of the flange base member 23C is at least equalto twice the first ply thickness, "T", measured at the straight hingeline "H_(L) " 21 of the first ply spring member 22. The flange heelmember is shown in FIG. 55 to be further constructed to have an endmostfirst ply extremity to provide a flange cap member 23E.

FIG. 66 illustrates in cross section a preferred embodiment of aspring-lock coupling structure where the first ply spring member 22 is aflat cantilever spring having a cylindrical first ply body memberconstituent 24A which resists a coupling tensile load "F" while in anon-deflected position. The second ply flange constituent 25 providesthe compression strength required to resist the longitudinal compressionforce, "F₁ " exerted on the flange load face 23B formed from the firstply extremity which provides the first ply flange member constituent 23.The outer flange heel extremity of the first ply flange memberconstituent 23D is connected to the load face extremity by a first plyflange base member 23C and serves to contain the second ply flangemember constituent 25 and prevent it from separating from the first plyflange member 23. One end of the second ply body member 26 provides thestraight hinge line 21 about which the flat cantilever spring member 22deflects to accept a suitably flanged mating spigot end structure.

FIGS. 66 and 68 illustrate the deflected position 72 of a flatcantilever spring member 22 connected to the first ply body member 24Aof a spring-lock coupling structure 20. These exampled springdeflections typify the behaviour of the flanged composite springsdescribed in the present invention and are most easily understood asdeflected cantilever beam members having a beam section areaapproximately equal to the product of a unit spring member width ,"W_(s) ", and the spring member thickness "T" measured at the hinge line21. The moment of inertia , "I" of composite spring members deflectingas a cantilever beam about a straight hinge line 21 is the second momentof area about a central axis of the cross section area of the springmember 22 located at the hinge line 21 of the spring member 22. In thepreferred embodiment of a flat cantilever spring member 22 the moment ofinertia, "I" of a unit width of spring member having a first plythickness "T" is taken to equal T³ /12.

To understand and appreciate the important contribution made by thenegative bevel angle "α" illustrated in FIGS. 55 and 58 which serves tolock the deflectable flange member 23 to a protruding spigot flangemember 20B the following analysis is provided to instruct how thebending moment equivalence must be maintained during the loadingoperation of a spring-lock coupling structure:

FIG. 66 shows the principal bending moment, "M_(o) ", which must beresisted by a unit width of the socket end flanged spring member 22. Thevalue of the bending moment "M_(o) " is calculated from the formula :M_(o) =F₁ h where "F₁ " equals the tensile load "F" applied to a unitwidth of the spring member at the hinge line 21 and "h" equals thedistance from the centerline of the spring member 22 to the center ofthe load face 23B where the tensile load is resisted by a compressiveforce "F₁ " equal and opposite to "F". As the free body vector diagramin FIG. 66 makes clear, the counterclockwise moment "M₀ " must be equaland opposite to a clockwise moment "M₁ ". The clockwise moment, "M_(o)", is calculated from the formula M₁ =P₁ L, where "P₁ " is the verticalforce vector component acting at the end of the cantilever spring member22, and "L" is the distance from the hinge line 21 ("H_(L) ") to thevertical force vector component, "P₁ ". The magnitude of the verticalforce vector "P₁ " is calculated from the formula P₁ =P₂ +P_(v), where"P_(v) " is the deflecting force required to deflect a unit width of aspring member 22 a vertical distance "H" and "P₂ " is the vertical forcevector resulting from the bevelled load face 23B of the flanged springmember 22 having a "lock angle" , "α" as shown in FIGS. 55 and 58. For anon-bevelled flange load face, such as characterize the couplingstructures shown in FIGS. 20, 21 and 22, the vertical force vector "P₂ "equals 0 and the vertical vector component "P₁ " will then equal "P_(v)". The value of "P₂ " is determined from the formula P₂ =F₁ tan α. Themoment, "M₁ " is the clockwise bending moment sufficient to prevent thespring member from deflecting enough to unlock the socket flange fromthe spigot flange. As can be noted from this analysis, a non-bevelledflange load face will require the entire bending moment M_(o) =F₁ h tobe resisted by the bending moment M₁ =P_(v) L. For large values of "F",this is impractical, since the value of "P_(v) " is usually small andthe use of a non-bevelled flange load face would require the springmember length "L" to be excessive.

FIGS. 69, 70 and 71 illustrate in cross section side elevation view apreferred embodiment of the spigot end 20B of a spring-lock couplingstructure 20. The flange length, "L_(F) ", and the flange face angles"α₁ " and "β" of the cylindrical flange spigot end 20BC are determinedprincipally by the spigot flange height "H_(F) ". The spigot end entryflange face angle "β" is preferably in the range of 5° to 30°. The lowerthe entry flange face angle "β" the greater the ease by which theflanged spigot end 20BC can be inserted into a coupling socket end 20Aproduced by the annular polygonal array of spring members 31. The spigotflange load face angle "α₁ " is preferably equal to the socket end"bevel lock" angle "α" shown in FIG. 55 and is preferably in the rangeof 10° to 20°. As shown in FIGS. 70 and 71 the length "L_(F) " of thespigot load flange 20B containing the spigot flange load face 26B isgoverned by three parameters: (1) the taper angle, "a", of the joint endfirst ply extremity 1 upon which the second ply extremity 2 is disposed;(2) the tensile hoop strength required of the second ply flanged bodyextremity 26 to resist longitudinal movement on the tapered first plyflanged body extremity when subjected to the coupling tensile load "F",; (3) the transverse shear strength of the twine material used as theflanged body first ply extremity 1. It has been empirically determinedthat the preferred total length "L_(F) " of a spigot end flange is from6 to 8 times the spigot end flange height "H_(F) ".

FIG. 58 is an enlarged cross section of the flange load face 23B of aspring-lock coupling structure first ply flange constituent 23. Thisfigure is helpful in noting that the flange load face ply 23B, as anextension of the first ply spring member 22, performs as a secondcantilever spring member connected to the primary cantilever springmember at a secondary hinge line 21A. When the flange load face ply 23Bis configured to provide a conical load face surface that conforms tothe conical surface of a spigot-end flange load face the secondary hingeline 21A is curved and the load face ply 23B becomes a secondarycantilever spring member which performs similar to the curved cantileverspring member 17 of the segmented coupling structure such as shown inFIG. 57.

FIG. 58 shows that the flange load face 23B contains a tangent linewhich makes a negative (clockwise) flange bevel angle "α" with atransverse vertical plane "Y--Y" containing the secondary hinge line 21Awhich joins the primary cantilever spring member 22 and the load face23B of the first ply flange constituent 23. From FIG. 58 it can also beseen that a vertical force vector "P₂ " is produced by the horizontalreaction force vector "F₁ " acting upon the flange face 23B which has abevel lock angle "α".

The maximum deflection "df" of a unit width of the load face cantileverextremity 23B subjected to a cantilever load equal to the flange faceforce "F₁ " can be calculated from the formula df=F₁ (H_(f))³ /3EI where"H_(f) " is the effective beam length of the deflecting member, "I" isthe moment of inertia (at 21A) of the secondary cantilever flange member23B equal to T³ /12 and "E" is the tensile modulus of elasticity of thetwine material comprising the flange member 23B. The deflection angle,"θ₁ " is the slope of the secondary cantilever deflection curve shown inFIG. 58 and under all conditions should remain less than the bevel lockangle "α". The formula used to determine the angle "θ₁ ". the anglebetween the undeflected load face surface and the deflected

load face measured in radians is θ₁ =arctan df/H_(f) =arctan F₁ (H_(f))²/3EI.

For an exampled flanged coupling spring having the configuration shownin FIG. 58 assume H_(f) =N₁ T and θ₁ =α. Thus the maximum unit load, "F₁", which can be registered before the angle "θ₁ " equals "α" can bedetermined from the formula F₁ =3EI (Tan α)/(H_(f))² =3E(T³ /12)(N₁ T)⁻²Tan α=0.25 E T Tan α/(N₁) ². Such a spring member is further stressed bythe transverse shear stress, "S_(s) " (=F₁ /T). The recommended designpractice in a preferred embodiment is to use "N₁ " values in the rangeof 0.5 to 3.0 and first ply thickness "T" values determined from theformula T=3F×N₁ /S_(T) where "S_(T) " is the allowable tensile stress ofthe first ply twine material, "N₁ " is the flange height multiplier(=H_(f) /T) and "F" is the unit tensile load to be resisted by thecoupler. The exampled tubular coupling structure had an inner diameterequal to 8 inches and a spigot and socket end configuration similar tothat shown in perspective cross section in FIG. 47. The couplerstructure was subjected to a maximum use pressure of 3.45 MPa (500 PSI)which produced a total coupling load of 11,423 kg (25,132 lb) and a unittensile load "F₁ " of 357 kg (785 lb) in each of 32 cantilever springmembers 25.4 mm (1 in) wide arranged on a 10 inch diameter as apolygonal array. A flange height multiplier value, "N₁ ", equal to 1 andan allowable tensile stress, "S_(T) " equal to 103.5 MPa (15,000 PSI)governed the selection of the first ply thickness, "T" which wascalculated from the formula T=3F₁ N₁ /S_(T) =3×785×1/15000=0.16 in. (4mm). From Table VI it can be seen that for a flanged spring having athickness of 4 mm, a length of 79 mm and a deflecting height of 13 mm itis neceasary to impart a deflecting force "P_(v) " of 187 Newtons (42lb) per spring. From the formula K_(T) =N_(s) K=N_(s) (P_(v) Tan β)where "N_(s) " is the total number of spring members 22 and "β" is thespigot end entry angle of 30°, it was determined that the total couplingassembly force "K_(T) " required to push the spigot end into the socketend was approximately equal to 32(42 Tan 30°)=831 lb (3696 N). It may benoted from Table VI that the vertical force "P_(v) " required to deflecta cantilever spring member diminishes as the cube of the spring length"L". To facilitate insertion of a flanged spigot end structure 20B whichproduces a given flange deflection height "H", it is only necessary toincrease slightly the length "L" of the spring member 22.

Tables IV, V and VI present the load relationships, dimension and otherparameters useful in the design of flanged flat composite cantileverspring members constructed as a preferred embodiment of the presentinvention. Such spring members are assumed to comprise a spring-lockcoupling structure which has a socket end made from a polygonal array ofspring members, and that the polygonal array comprises spring membershaving uniform spring width and arranged to form a regular polygon suchas shown in FIG. 65.

Table IV enables a designer to select the required first ply thickness"T" to provide a spring-lock coupling structure able to resist a givenunit tensile load "F" applied to a unit width of the spring member.Table IV assumes the composite material has an allowable design strengthof 104 MPa (15,000 PSI) and presents the vertical force "P₂ " whichreacts against the bevelled flange load face 23B. Table IV also presentsthe minimum length "L", as shown in FIGS. 62 and 66, required of thespring member 22 to provide the minimum unit bending moment, "M₁ " (=L₁P₁) needed to equal the unit bending moment "M_(o) " (=F₁ h) produced bythe compressive load "F₁ " applied to the flange load face 23B center atthe compressive load offset distance "h".

Table V provides guidelines for the design of pressure-sealed compositespring-lock coupling structures having the flanged spigot endconfiguration represented by a preferred embodiment of this inventionsuch as exhibited in FIG. 46. Table V presents the maximum internalpressure, "P", that can be resisted by a sealed coupling structurehaving an inner diameter "D" ranging from 2 to 30 inches. Table V alsopresents the first ply hinge line thickness "T" able to resist a tensileload "F" per 25.4 mm (1 inch) of spring member 22 width. The tensileload "F" is in turn resisted by a compressive force "F₁ " of equalmagnitude applied to the center of the load face 23B of the flangemember 23 as shown in FIG. 66.

Table VI presents design guidelines for tubular spring-lock couplingstructures As schematically depicted in FIG. 66 two composite springproperties are of special significance in the flanged spring embodimentsof the present invention. One property is the force "P_(v) " required todeflect the flange attachment end of the spring member a given distance"H". The second property is the stress imposed on the spring membermaterial at the spring hinge line "H_(L) ". Table VI also presents themagnitude of vertical force "P_(v) " that is required to deflect a flatflanged cantilever spring member 22 a distance "H". The "P_(v) " valuesshown in Table VI were calculated from the formula P_(v) =3H EI/L³,where the vertical spring deflecting force, "P_(v) " is measured inNewtons (N), the spring deflection height "H" is measured in mm, thespring length, "L" is measured in mm, from the hinge line "H_(L) " 21 tothe flange face point of vertical force application, "E" is the tensilemodulus of elasticity measured in Giga Pascal (GPa) and "I" is themoment of inertia of a spring member section having a unit width of 25.4mm (1 inch) and a uniform thickness "T" measured in mm. The value of "E"used in Table VI is 24 GPa (3.5×10⁶ PSI). The value of "I" for a unitwidth spring is T³ /12 mm⁴. Table VI values are also based on theassumption that each spring member 22 has a length "L" equal to 7H andthat the maximum allowable spring deflection height "H" is based on theformula H=N'T, where "N'" is an arbitrary numerical multiplier whichgoverns the amount of socket end spring deflection required to enableinsertion of a flanged spigot end 20B. The deflecting force "P_(v) " isused to determine the total force , "K_(T) " required to push a flangedspigot end into a socket end 20A having a polygonal array 31 ofdeflecting spring members 22.

Table VII provides the axial force "K" needed to deflect each springmember an amount "H" equal to 4T. The total deflecting force "K_(T) "can be determined from the formula K_(T) =N_(s) K=N_(s) P_(v) Tan β. Forexample, using values presented in Table VI for an eight-sided regularpolygonal array 31 of spring members 22 such as depicted in FIGS. 45, 46and 65, the total vertical deflecting force produced by eight springmembers 79 mm long having an individual spring thickness "T" equal to 4mm which deflect "H" equal to 13 mm equals 8P_(v) =8×187N=1496N(336 lb).A flanged spigot end 20B with an entry flange face angle "β" equal to30° will require an axial coupling assembly force, K_(T) (=8P_(v) Tan β)of approximately 864 N (194 lb).

Tables VII and VIII provide the dimensions and performancecharacteristics of typical tubular spring-lock coupling members used aspressure pipe and having construction features and configurationssimilar to those shown in FIGS. 4 and 9. The column headings in TablesVII and VIII are symbols which designate the following designparameters:

"F"=COUPLING TENSILE LOAD PER INCH OF CIRCUMFERENCE (LB/IN)

"N_(s) "=NUMBER OF SIDES TO THE REGULAR POLYGON FORMED BY A SIMILARNUMBER OF FLAT SOCKET₋₋ END COUPLING SPRING MEMBERS HAVING A UNIT WIDTHOF ONE INCH

"T"=THICKNESS OF EACH CANTILEVER COMPOSITE SPRING MEMBER MEASURED AT THEHINGE LINE (IN)

"L"=LENGTH OF CANTILEVER COMPOSITE SPRING MEMBER MEASURED FROM HINGELINE TO CENTER OF FLANGE LOAD FACE MEMBER (IN)

"D_(s) "=COUPLING INTERIOR SPRING DIAMETER EQUAL TO THE DIAMETER OF ACIRCLE INSCRIBED WITHIN A REGULAR POLYGON WITH "N_(S) " SIDES ONE INCHHWIDE (IN)

"D"=INSIDE DIAMETER OF SPRING-LOCK COUPLING BODY MEMBER USED AS APRESSURE PIPE (IN)

"P"=MAXIMUM INTERNAL PRESSURE RESISTED BY A COUPLING STRUCTURE WITH APIPE WALL THICKNESS EQUAL TO 2 T (PSI)

"K"=MAXIMUM AXIAL FORCE REQUIRED TO DEFLECT EACH SOCKET END FLANGEDSPRING MEMBER DURING COUPLER ASSEMBLY (LB)

"P₂ "=FLANGE LOCKING FORCE (LB)

"α"=FLANGE LOAD FACE LOCK ANGLE (DEGREES)

"H"=MAXIMUM SPRING MEMBER DEFLECTION (IN)

"S_(T) "=MAXIMUM TENSILE STRESS PRODUCED IN SPRING MEMBER AT HINGE LINEFROM MAXIMUM DEFLECTION OF SPRING MEMBER

Tables VII and VIII are based upon an allowable first ply tensilestrength of 104 MPa (15,000 PSI) and assume the spigot flange height"H_(F) " equals "H" which in turn is assumed to equal 4 T. The maximumtensile stress to which the spring member material is subjected whendeflected an amount "H" is calculated from the formula S_(T) =M_(v) c/Iwhere "M_(v) " is the bending moment due to the deflecting force "P_(v)" and is calculated from the formula M_(v) =P_(v) L. The section modulusterm c/I is calculated from the formulas c=T/2 and I=T³ /12. The maximumstress , "S_(T) " is calculated from the formula S_(T) =6P_(v) L/T² forspring members having a unit width of one inch. As shown in Table VIIIthe maximum stress to which a spring member is subjected when having thedimensions shown is less than 30 percent of the maximum tensile strengthof the spring member material shown in Table II. The following formulawas used to calculate the coupling spring diameter "D_(s) ":D_(s) =W_(s)Tan (180/N_(s)) where "W_(s) "=1 inch. Tables VII and VIII shows theminimum bevel lock angle "α" required to prevent the flange member from"unlocking" due to the unit tensile load "F". Since "F"="F₁ ", theminimum load face bevel lock angle "α" is equal to the angle having atangent value equal to the ratio P₂ /F. The maximum use pressure "P"shown in Table VII was calculated from the formula P=4F/D. The value of"K"was calculated from the formula K=P_(v) Tan β where"β" is the taperangle of the leading insertion end of a bevelled spigot flange , whichfor purposes of illustration was selected as equal to 20° for valuesshown in TAble VII.

                                      TABLE IV                                    __________________________________________________________________________    DESIGN PARAMETERS FOR SPRING LOCK COUPLER SOCKET-END MEMBERS                   ##STR1##                                                                             ##STR2##                                                                             P.sub.1 (= F tan α)                                                                    ##STR3##                                               S = 104 MPa                                                                          KN (lb)        FOR FOR  FOR                                            (15000 PSI)                                                                          α = 10°                                                               α = 15°                                                               α = 20°                                                               h = T                                                                             h = 1.5T                                                                           h = 2T                                  KN     mm     KN   KN   KN   mm  mm   mm                                      (lb)   (in)   (lb) (lb) (lb) (in)                                                                              (in) (in)                                    __________________________________________________________________________     4.4    1.5   0.8  1.2  1.6   6   9    11                                     (1000) (0.06)  (176)                                                                              (267)                                                                               (364)                                                                            (0.22)                                                                            (0.34)                                                                             (0.45)                                   8.9    3.3   1.6  2.4   3.2 12  18    25                                     (2000) (0.13)  (353)                                                                              (536)                                                                              (728)                                                                             (0.49)                                                                            (0.73)                                                                             (1.00)                                  17.8    6.6   3.1  4.8   6.5 25  38    51                                     (4000) (0.27)  (705)                                                                             (1072)                                                                             (1456)                                                                             (1.00)                                                                            (1.51)                                                                             (2.00)                                  35.6   12.0   6.3  9.5  13.0 51  76   101                                     (8000) (0.53) (1411)                                                                             (2143)                                                                             (2912)                                                                             (2.00)                                                                            (3.00)                                                                             (4.00)                                  45.0   15.0   7.8  12.0 16.0 63  95   127                                     (10000)                                                                              (0.67) (1763)                                                                             (2680)                                                                             (3640)                                                                             (2.50)                                                                            (3.75)                                                                             (5.00)                                  54.0   18.0   9.4  14.0 19.0 76  114  152                                     (12000)                                                                              (0.80) (2116)                                                                             (3215)                                                                             (4368)                                                                             (3.00)                                                                            (4.50)                                                                             (6.00)                                  __________________________________________________________________________

                                      TABLE V                                     __________________________________________________________________________    DESIGN PARAMETERS FOR SPRING LOCK                                             COUPLER SOCKET END MEMBERS                                                               "T" (= F/S)                                                                           "P" (= 4F/D)                                               "F" (= PD/4)                                                                             SPRING PLY                                                                            COUPLED PIPE PRESSURE                                      FLANGE FACE                                                                              THICKNESS                                                                             PRODUCING FLANGE END LOAD                                  LOAD PER 24.4 mm                                                                         S = 124 MPa                                                                           FOR GIVEN PIPE I.D. ("D")                                  SPRING WIDTH                                                                             (18,000 PSI)                                                                          MPa (PSI)                                                  kN         mm      "D" (mm)                                                                            51  203 254 762                                      (lb)       (lb)    (in)   2   8   10  30                                      __________________________________________________________________________     4.45      1.27          13.8                                                                               3.5                                                                               2.8                                                                              0.9                                      (1000)     (.05)          (2000)                                                                            (500)                                                                             (400)                                                                            (133)                                     8.89      2.79          27.6                                                                               6.9                                                                               5.5                                                                              1.8                                      (2000)     (.11)          (4000)                                                                           (1000)                                                                             (800)                                                                            (266)                                    17.79      5.59          55.2                                                                              13.8                                                                              11.0                                                                              3.7                                      (4000)     (.22)          (8000)                                                                           (2000)                                                                            (1600)                                                                            (533)                                    26.69      8.38          82.8                                                                              20.7                                                                              16.6                                                                              5.5                                      (6000)     (.33)         (12000)                                                                           (3000)                                                                            (2400)                                                                            (800)                                    35.58      11.18         110.0                                                                             27.6                                                                              22.1                                                                              7.4                                      (8000)     (.44)         (16000)                                                                           (4000)                                                                            (3200)                                                                            (1066)                                   44.48      13.97         138.0                                                                             34.5                                                                              27.6                                                                              9.2                                      (10000)    (.55)         (20000)                                                                           (5000)                                                                            (4000)                                                                            (1333)                                   53.38      16.76         166.0                                                                             41.4                                                                              33.1                                                                              11.0                                     (12000)    (.66)         (24000)                                                                           (6000)                                                                            (4800)                                                                            (1600)                                   __________________________________________________________________________

                  TABLE VI                                                        ______________________________________                                        DESIGN PARAMETERS FOR SPRING-LOCK                                             COUPLER SOCKET END MEMBERS                                                                 N.sup.1                                                          (H = N.sup.1 × T)                                                                      2      3      4    5    6    7                                 ______________________________________                                        T = 2.5 mm                                                                             H      mm      5    8   10   13   15   18                            (0.10 in)       (in)   (0.2)                                                                              (0.3)                                                                              (0.4)                                                                              (0.5)                                                                               (0.6)                                                                              (0.7)                                 L      mm     35   53   71   89   107  124                                           (in)   (1.4)                                                                              (2.1)                                                                              (2.8)                                                                              (3.5)                                                                               (4.2)                                                                              (4.9)                                 P.sub.v                                                                              N      285  125  71   45   31   22                                            (lb)    (64)                                                                              (28) (16) (10)  (7)  (5)                          T = 4 mm H      mm      8   13   15   20   23   25                            (0.15 in)       (in)   (0.3)                                                                              (0.5)                                                                              (0.6)                                                                              (0.8)                                                                               (0.9)                                                                              (1.0)                                 L      mm     53   79   106  135  160  187                                           (in)   (2.1)                                                                              (3.1)                                                                              (4.2)                                                                              (5.3)                                                                               (6.3)                                                                              (7.4)                                 P.sub.v                                                                              N      427  187  107  67   49   36                                            (lb)    (96)                                                                              (42) (24) (15) (11)  (8)                          T = 5 mm H      mm     10   15   20   25   30   35                            (0.20 in)       (in)   (0.4)                                                                              (0.6)                                                                              (0.8)                                                                              (1.0)                                                                               (1.2)                                                                              (1.4)                                 L      mm     71   107  142  178  213  249                                           (in)   (2.8)                                                                              (4.2)                                                                              (5.6)                                                                              (7.0)                                                                               (8.4)                                                                              (9.8)                                 P.sub.v                                                                              N      565  254  142  89   62   45                                            (lb)   (127)                                                                              (57) (32) (20) (14) (10)                          T = 6 mm H      mm     13   20   25   30   38   45                            (0.25 in)       (in)   (0.5)                                                                              (0.8)                                                                              (1.0)                                                                              (1.2)                                                                               (1.5)                                                                              (1.8)                                 L      mm     89   134  178  223  266  312                                           (in)   (3.5)                                                                              (5.3)                                                                              (7.0)                                                                              (8.8)                                                                              (10.5)                                                                             (12.3)                                 P.sub.v                                                                              N      707  316  178  116  80   58                                            (lb)   (159)                                                                              (71) (40) (26) (18) (13)                          ______________________________________                                    

                  TABLE VII                                                       ______________________________________                                        DESIGN PARAMETERS FOR PRESSURE PIPE                                           SPRING-LOCK COUPLER MEMBERS                                                   F           T        L    D.sub.S                                                                              D    P       K                               (LB)  N.sub.S                                                                             (IN)     (IN) (IN)   (IN) (PSI)   (LB)                            ______________________________________                                        1000   6    0.07     1.75 1.73   1.00 3750     22                             1000   8    0.07     1.75 2.40   1.75 2290     29                             1000  16    0.07     1.75 5.00   4.36  920     58                             2000   8    0.13     4.36 2.40   1.00 7400     29                             2000  16    0.13     3.46 5.00   3.70 2150    115                             2000  24    0.13     4.36 7.60   6.25 1275     86                             3000  16    0.20     5.52 5.00   3.00 4000    144                             3000  24    0.20     5.19 7.60   5.60 2150    260                             3000  32    0.20     5.94 10.2   8.15 1475    230                             4000  24    0.27     11.0 7.60   5.00 3250     86                             4000  32    0.27     8.72 10.2   7.50 2125    230                             4000  48    0.27     7.62 15.3   12.6 1270    518                             5000  32    0.33     10.9 10.2   6.80 2900    288                             5000  48    0.33     8.65 15.3   11.9 1675    864                             5000  60    0.33     14.8 19.0   15.8 1270    216                             ______________________________________                                    

                  TABLE VIII                                                      ______________________________________                                        DESIGN PARAMETERS FOR SPRING-LOCK                                             COUPLER SOCKET END MEMBERS                                                                                        MINIMUM                                   F            T       L    H    P.sub.2                                                                            β   S.sub.T                          (LB/IN)                                                                              N.sub.S                                                                             (IN)    (IN) (IN) (LB) (°)                                                                             (PSI)                            ______________________________________                                        1000    6    .070    1.75 0.27  96  5.5      23365                            1000    8    .070    1.75 0.27  96  5.5      23365                            1000   16    .070    1.75 0.27  96  5.5      23365                            2000    8    0.13    4.36 0.53 153  4.4      14718                            2000   16    0.13    3.46 0.53 193  5.5      23363                            2000   24    0.13    4.36 0.53 153  4.4      14718                            3000   16    0.20    5.52 0.80 272  5.2      20688                            3000   24    0.20    5.19 0.80 289  5.5      23363                            3000   32    0.20    5.94 0.80 252  4.8      17829                            4000   24    0.27    11.0 1.07 243  3.5       9271                            4000   32    0.27    8.72 1.07 306  4.4      14717                            4000   48    0.27    7.62 1.07 350  5.0      19285                            5000   32    0.33    10.9 1.33 382  4.4      14716                            5000   48    0.33    8.65 1.33 482  5.5      23361                            5000   60    0.33    14.8 1.33 282  3.2       7989                            ______________________________________                                    

EXAMPLE V

FIGS. 3A, 3B, 50, 51, 52, 53 and 54 illustrate various couplingstructures that teach a preferred embodiment of this invention and whichare hereafter referred to in this specification as the "SEGMENTED" typeof coupling structure 10. FIGS. 3A and 3B are perspective exploded viewsof two semi-circular segmented coupling structure members having flangedspring members at each end which are assembled and held together by apair of retaining sleeves. FIG. 3A illustrates a segmented couplingstructure 10 comprising a double flanged semi-circular couplingstructure 12 which comprises a first ply spring member 17 connected to afirst ply flange member 13 and a first ply body member 19. Two of thecoupling structures 12 are held together by a circular retaining sleevemember 18. FIG. 3B illustrates a second configuration of the segmentedcoupling structure 12 which comprises a cylindrical array of paralleladjacent uniformly spaced flanged spring members 13A which are deflectedduring assembly by a retaining sleeve member 18. An alternateconstruction of the coupling structure shown in FIG. 3B (not shown)involves making the second ply semi-circular body member 16 as a seriesof individual second ply hoop rings to provide a flexible couplingstructure able to bend at least 5° in any direction about the couplingstructure central axis 76A.

FIG. 50 is a cross section perspective side elevation view of apreferred embodiment of this invention and illustrates details ofconstruction of the coupling structure shown in FIGS. 3A and 3B. Thesegmented coupling structure 10 connects two mating flanged joint pipeends 29 such as may be made according to the teachings of U.S. Pat. No.4,385,644. The joint ends of the pipe are configured to contain acompressible annular face seal 38A as illustrated in FIG. 56. Theretaining sleeve structure 18 compresses the semicircular spring member17 to deflect it as a cantilever spring about a curved hinge line 11.

FIG. 32 shows a cross section view of a double-flanged couplingstructure 10 in process of manufacture upon a coupling formingapparatus.

FIG. 33 shows a single flange semi-circular type of coupling structurein process of manufacture. This type of coupling structure has one endwhich serves as a structural flange to contain a pressure plug such asused to seal a pressure vessel end.

FIGS. 53 and 54 are identical to FIG. 50 as regards the couplingstructure 10 used to connect flanged pipe joints 29. However, thesefigures dipict special pipe end adapter rings 57 which are made of acomposite comprising circumferential twines 8 placed upon longitudinaltwines 9. The adapter rings 57 are configured to enable sealing pipejoint ends which are identical and which employ sealing means similar tothat shown in FIG. 50.

FIGS. 51 and 52 illustrate other joint ends of composite pipe 29 whichmay be connected and sealed by means of the semicircular segmentedcoupling structure 10 shown in FIGS. 3A and 3B.

FIGS. 56, 57 and 59 identify the principal dimensions and load vectorswhich govern the design of segmented semi-circular couplers havingflanged semi-circular cantilever spring members 17 which resist acoupling tensile load "F" while the spring member is in a deflectedposition 72.

FIG. 60 illustrates the perspective view of the principal plies whichcomprise the flanged spring and body members of a segmented typecoupling structure.

FIG. 61 illustrates the curved hinge line 11 which characterizes thecurved cantilever spring members 17 of segmented coupling structureswhich embody teachings of this invention.

FIG. 56 depicts the first ply configuration of the flange constituent ofa segmented type of coupling structure 10. This flange constituent 13 isconfigured to have an interior flange load face extremity 13B whichresists a compressive load "F₁ ", and to comprise a flange base member13C as well as a flange heel member 13D which is constructed so that theendmost extremity of the flange heel 13D extends radially outward from acentral axis 76A to a height at least equal to the height of the flangeload face member 13B.

The flange heel member 13D is configured to have a partially circularsection and the radius of the curved extension of the flange base member13C is designated as "R_(F) " which is at least equal to twice the firstply thickness "T" measured at the curved hinge line 11.

FIG. 59 illustrates in cross section a preferred embodiment in which thefirst ply spring member 17 is semi-circular and resists a couplingtensile load "F" while deflected by a spring deflecting load "P_(R) "imposed by an encircling retaining sleeve structure 18. A terminus ofthe semi-circular second ply body constituent 16 provides asemi-circular curved hinge line 11 about which the semi-circular curvedspring member 17 deflects during and following installation of acomposite retaining sleeve structure 18A. The width "W_(R) " of thecomposite retaining sleeve 18A is at least equal to the width "W_(F) "of the second ply flange member 15 and has an inner diameter "D₂ " lessthan the undeflected outside diameter "D_(U) " of the exterior flangesurface of two connected semicircular coupling structures 10. Thecoupling structure connects two mating flanged joint pipe ends 29containing a compressible annular face seal 38A. The retaining sleevestructure 18 resists a diametral growth of the exterior flange surfacewhen segmented coupling structures having conically bevelled flange loadfaces 13B are subjected to tensile coupling loads. The less thediametral growth of the coupling structure flange face surfaces, theless the separation between the flange joint pipe ends and the less theconcomitant loss of face seal compression.

The following analysis refers to a typical coupling structure of thetype shown in FIG. 3A and schematically illustrated in FIGS. 56 and 59.Such coupling structures comprise two semi-circular segmented couplingstructures 10 connected by an encircling retaining sleeve 18 whichdeflects each flange member to press it against the flange of a pipejoint 29. The semi-circular coupling structures have a pair of opposingflange members 14 which are configured to have load face surfaces 13Bthat are bevelled at a 45° angle. Such a bevelled flange couplingstructure is used to connect and provide sealing integrity between thecomposite pipe joints 29 having appropriate annular face sealprovisions. The pressure sealing of such pipe joints depends upon thecompression of an annular face seal 38A having an uncompressed sealwidth "D_(o) ". The retaining sleeves 18 used to connect thesemi-circular coupler halves 10 serve not only to deflect and prestressthe semi-circular spring members 17 but also to preload in compressionthe pipe joint composite flange members 29. The connected couplingstructures together with the pair of retaining sleeves 18, are designedso that the maximum allowable elongation "ΔL" of the coupling structure10 does not exceed 20 percent of the compressible seal width, "D_(o) ".The maximum allowable elongation , produced by the combination oftemperature and other service loads, is expressed by the formula:ΔL=0.2D_(o) =ΔK+ΔD_(R), where ΔK equals the change in length of thecoupler first ply body constituent 19 due to a raise in temperature ofthe first ply body material as well as due to the tensile load resistedby the coupler first ply body constituent 19 and where ΔD_(R) is theaverage increase in the diameter "D_(R) " of each retaining sleevestructure 18 which connects and encircles the two coupling halves.Referring to FIG. 56 it is easiest to calculate the values of ΔK andΔD_(R) by calculating the coupling tensile load "F" per unit length ofcircumference and then calculating the total resulting strain in thefirst ply spring member 17 and body member 19 material. The followingprocedure illustrates how this was done for a segmented double flangedcoupling structure 12 having a first ply body member 19 sujected to atensile coupling load equal to 559200 Newtons (125,663 lb). The innerdiameter of the body member "D_(B) " was 254 mm (10 in). The unitcircumferential coupling tensile load "F" communicated to the flangedspring member 17 by the body member 19 was calculated as follows: (1)Body member circumference=3.1416×D_(B) =3.1416×254= 798 mm ; (2)Coupling tensile load per unit length ofcircumference="F"=559,200/798=700 N/mm (4000 lb/in). It was assumed thatthe allowable tensile strength "σ_(A) " of the first ply material isequal to one half the material's transverse shear strength of 2.27 GPa(33,000 PSI). Thus the allowable tensile strength of the first ply=113.5GPa. The tensile modulus of elasticity , "E", of the first ply materialwas assumed to be 24.3 GN/m² (3.51×10⁶ PSI). Thus the strain value "ε₁ "of the first ply material at a stress equal to the maximum allowablestrength "σ_(A) " was determined from the formula ε₁ =σ_(A) /E=0.0047mm/mm (0.0047 in/in). It was further assumed that the length "L_(c) " ofthe coupling body member 19 was 152 mm (6 in). Under the maximum tensileload, it was calculated that the coupling body member 19 would elongatean amount ΔK₁ where ΔK₁ =ε₁ L_(c) =0.0047 (152)=0.716 mm (0.028 in). Itwas further assumed that the temperature increase, "ΔT", in the couplingbody material was 93° C. (200° F.) and that the coefficient of linerthermal expansion, "e_(T) " equals 11×10⁻⁶ cm/cm/° C. Under such atemperature increase it was calculated the coupling body material 19would experience a thermal strain ε_(T) =ΔT e_(T) =93×11×10⁻⁶ =0.001cm/cm and that the coupler body member length of 152 mm would increasean amount "ΔK_(T) " where ΔK_(T) =0.001 (152)=0.155 mm. (0.006 in).Since the total coupling elongation "ΔK" equals the sum ΔK₁ +ΔK_(T), thevalue of ΔK was calculated to equal 0.871 mm (0.034 in).

For a bevelled flange angle "α₂ " equal to 45°, the unit load "F"=700N/mm imposes a reaction pressure "P_(E) " upon a unit circumferentialwidth of the retaining sleeve 18 equal to F/W_(F) where "W_(F) " equalsthe flange width contacting the retaining sleeve. If the flange width"W_(F) " is assumed to equal 76 mm (3 in) then the reaction pressure"P_(E) " is determined to equal 700/76=9.2 MPa (1333 PSI). The reactionpressure "P_(E) " exerts a hoop stress on the retaining sleeve which isequal to "σ_(R) " and which is determined from the formula σ_(R) =P_(E)D_(R) /2T_(R), where "T_(R) " equals the thickness of the retainingsleeve material resisting the hoop stress imposed by the reactionpressure. The value "T_(R) " determines the amount the retaining sleeve18 will strain and thus increase the sleeve diameter The sleeve changein diameter "ΔD_(R) " can thus be controlled by increasing the s1eevethickness "T_(R) ". The hoop tensile stress in the retaining sleevematerial, "σ_(R) ", and the tensile modulus of the retaining sleevematerial "E_(R) " determine the allowable retaining sleeve strain "ε_(R)" from the formula ε_(R) =σ_(R) /E_(R). It was assumed in the exampledcalculation that the retaining sleeve material was identical to thefirst ply material.

The allowable strain "ε_(A) " is determined from the allowable change inthe retaining sleeve inner diameter "ΔD_(R) " from the formula ε_(A)=ΔD_(R) /D_(R). If ΔD_(R) is required to be equal or less than ΔK, andthe sleeve inner diameter "D_(R) " is assumed to equal "D_(B) "=254 mmthen the allowable strain "ε_(A) " is equal to 0.871/254=0.0034 mm/mm.The allowable stress in the retaining sleeve "σ_(A) " is then determinedto equal E×0.0034=24,300 (0.0034)=83 MPa (12,000 PSI). Since σ_(R) mustequal σ_(A) if the retaining sleeve diametral change, "ΔD_(R) " is toequal "ΔK", then the thickness "T_(R) " of the retaining sleevecircumferentially oriented twine material 8 is determined from theformula T_(R) =P_(E) D_(R) /2σ_(A). From the above calculation T_(R)=(9.2×254/2 (83)=14 mm (0.55 in). The total coupling elongation, "ΔL" inthis example equals ΔK+ΔD_(R) =0.871+0.871=1.74 mm (0.068 in).

If the maximum coupling structure elongation is not to exceed 20 percentof the diameter of a compressible "O" ring face seal 38A then the "O"ring diameter calculated from this example must at least equal 5ΔL or 9mm (0.343 in).

Since the thickness of the first ply body member 19 controls theallowable strength value, "σ_(A) " it can be seen that the presentinvention permits an easy method to reliably control the elongation ofan assembly of two tensile-loaded segmented semi-circular couplingstructures 10. The thickness "T" of the first ply 1 which provides theallowable strength "σ_(A) ", is determined from the formula T=F/σ_(A).For the above example the first ply thickness "T" equals 700/113=6.19 mm(0.24 in). The coupler elongation "ΔL" can be reduced by simplyincreasing the thickness of the first ply 1.

FIGS. 56, 57 and 59 illustrate a deflection 72 of the curved flangemember 14 attached to the curved cantilever spring member 17 belongingto a semi-circular segmented coupling structure 10 when it is assembledand preloaded by a retaining sleeve member 18. Calculations used todesign the curved circular segment spring members 17 shown in FIG. 57and used in semi-circular segmented coupling structures similar to thoseshown in FIGS. 3A and 3B are based upon experimentally derived formulasusing the twine composite properties shown in Table II. The formula todetermine the maximum allowable curved spring deflection angle "θ"illustrated in FIGS. 56 and 57 is=8.8×10⁻⁷ ×σ_(A) where "θ" is measuredin radians and "σ_(A) " is the allowable tensile stress of the first plyspring material measured in PSI. The formula to determine the maximumallowable spring deflection force "F₂ " (shown in FIG. 57 ) per unitwidth of the curved spring member 17 is F₂ =0.2T×σ_(A). The unitinstallation force, "F_(K) " applied to a retaining member 18 isapproximately equal to 0.07 F₂. FIG. 57 is an enlarged view of the shortcircular segment curved spring member 17 employed in segmented couplingswhich embody the present invention. The circular segment curved springmember has a length "L'" equal to the product of the spring angle "Φ"and the inner radius "R" of the spring, where the spring angle "Φ" ismeasured in radians. The spring angle recommended for the curved springmember of segmented coupling structures which exhibit a preferredembodiment is π/4 radians (45°). The deflection of the end of such acurved cantilever spring is radially inward with respect to a centralaxis of a two piece segmented circular coupling structure. Referring toFIG. 57 the angular magnitude of the radial deflection is "θ", "F₂ " isthe magnitude of the force vector required to deflect the curvedcantilever spring 17 an amount "θ", and "T" is the thickness of thefirst ply spring member measured at the hinge line 11. It has beendetermined that an angular deflection of less than one degree of thecurved cantilever spring (θ=1° or less) provides an adequate preloadforce to firmly lock in place the retaining sleeve 18 to prevent it frombeing shifted or easily removed when the coupling structure is notsubjected to a tensile load "F". An exampled coupling assembly used aunit installation force "F_(K) " approximately equal to 10 lb per 0.2in. of first ply thickness. A first ply thickness equal to 0.2 inchesproduced a spring deflection force "F₂ " equal to 286 lb. and a springmember stress equal to 7150 PSI (σ=5 F₂ /T). The resulting springdeflection, "θ", was 0.0063 radians or 0.4°. In this example the springradius "R" equalled the first ply spring member thickness "T", and thefirst ply material tensile modulus, "E" was equal to 3.5×10⁶ PSI. Fromthis example it was seen that a deflection of the circular segmentcurved spring member 17 in the manner depicted in FIGS. 56 and 57pre-stresses the spring and assures an intimate contact between thecoupling flange load face member 13B and the mating load face of aflanged joint member 29 connected by the coupling structure. The twopiece segmented coupling shown in FIGS. 3A and 3B depend upon thecircular retaining sleeve members for coupler integrity and optimumcoupling structure performance. As is illustrated in FIG. 57 thesemi-circular flanged cantilever spring member 17 resists the axiallydirected shear force "F_(s) " produced by and equal to the couplertensile load, "F". This shear force produces a unit transverse shearstress "S_(s) " in the curved cantilever spring member which can becalculated from the formula S_(s) =F_(s) sin Φ/T where "Φ" is theangular length of the circular spring segment. For a first ply circularspring thickness "T" equal to 0.2 inches and a curved spring angle "Φ"equal to 45°, a tensile load "F" equal to 2,000 pounds per inch ofcircumference of the coupling body member will produce a unit transverseshear stress in the first ply segmented coupling spring member equal toapproximately 7071 PSI (48.8 MPa). From Table II it can be seen thatthis is less than 25% of the maximum transverse shear strength of atypical first ply composite material. A recommended practice is to makethe retaining sleeve member 18 sufficiently thick and rugged towithstand installation forces and reduce diametral enlargement of thesleeve when deflecting the curved spring member 17.

EXAMPLE VI

FIG. 72 is a partially fragmented sectional perspective view of animpermeable tubular composite structure similar to that employed as thepressure resistant body member 30 of a flanged spring-lock couplingstructure or a flanged composite pipe 29 connected by the segmentedcomposite coupling structure 10 disclosed in this invention. The flangedtubular body member 30 comprises an impermeable inner liner 45 made of apolymeric resin, such as a urethane elastomer, having a capability toremain impermeable when stretched and simultaneously subjected to atensile strain value at least equal to 0.020 mm/mm in thecircumferential as well as the longitudinal direction. The linerprovides the tubular composite structure with a pressure sealingmembrane able to resist pressures as great as 100 MegaPascal (15,000PSI). The tubular composite structure which resists the circumferentialand longitudinal stresses produced when the structure is subjected to anend load and/or internal pressure comprises an inner third ply 27 ofcontinuous helically wound CIRC twines 8 surmounted by a first ply 1 ofparallel longitudinally oriented LONGO twines which are flared orotherwise configured at each end of the tubular member to provide aspigot or socket end coupling flange structure. The ply of parallelLONGO twines is covered by an exterior second ply 2 composite bodystructure such as may be formed by a single ply of circumferentialfilament wound twines 8. As seen in FIG. 72, and more clearly from theelliptically shaped enlargement view, the LONGO ply twines 9 and theCIRC ply twines 8 of the composite tube structure 30 comprise individualtwines 7 bonded by a hardened liquid matrix 6A used to impregnatehelically configured strands of continuous filament reinforcements 5which are individually covered and enclosed by a twine coat 47. Thematerial comprising the twine coat 47 which covers each twine is mostcommonly the same hardenable liquid bonding matrix material 6 used toimpregnate the helically configured twined strands. The twine coatmaterial 6B may also comprise, in addition to the matrix material, 6 anadditional layer of a compatible matrix material 6C. The additionallayer may have a variable thickness and may also serve to provide ameans of controlling the distance separating adjacent twines 7. Aprincipal function of the twine coat 47 is to facilitate the physicalseparation of at least some of the individual twines comprising the CIRCand LONGO plies when the tubular composite structure becomes stressed ina manner that results in a change in the diameter or length of thetubular structure. This is possible due to the fact that the twine coat47 is weaker in shear and tension than the filament-reinforced compositematerial comprising the twine 7. The impermeable and elastomeric natureof the inner liner 45 prevents the tubular structure from leaking orlosing pressure when the individual twines comprising thecircumferentially wound CIRC ply or the longitudinally oriented LONGOply physically separate to accomodate the changes in tube dimension thatresult when the compsoite tubular structure is stressed.

The composite tube outer second ply body member 26 is constructed to beimpermeable whenever the tubular structure is designed to operate whilesubmerged, buried or exposed to weather.

The separation distance 47A between the individual twines comprising theCIRC ply 2 or the LONGO ply 1 can range from as little as 0.1 micron toas much as twenty times the thickness of an individual ply twine 7. Thetwine separation distance or space between adjacent twines 47A may becontrolled by the twine coat 47 and the physical properties anddimensions of the material 6B comprising the twine coat. The separationdistance 47A between individual adjacent twines in the same compositeply structure is thus used not only to accomodate dimensional changesproduced in the tubular composite structure 30 by stresses resultingfrom pressure, torque and end loads, but also to increase the stiffnessof the composite wall structure by increasing the moment of inertia,"I", of either or both tubular twine plies.

EXAMPLE VII

FIGS. 23, 24 and 25 illustrate apparatus which can be employed in theconstruction of composite coupling structures that typify the preferredembodiments of this invention. FIGS. 27 , 32, and 33 illustrate couplingforming apparatus 58 used to make segmented type coupling structures.FIG. 23 is a perspective view of a rotatable cylindrical mandrelstructure 51 upon which segmented semi-circular couplings 10 and tubularspring-lock coupling structures 20 can be made. The mandrel 51 issupported by axel members 52 and 54. The axel member 52 is a turning endaxel permanently attached to the mandrel and having a sprocket gear 52A. The axel member 54 is attached to a removable section of mandrel 51A.When a tubular spring-lock type coupling structure is made on themandrel 51 and the sprocket end coupling forming structure (not shown)the removable mandrel portion 51A is removed to enable removal of atubular spring-lock coupling structure made on the mandrel. The mandrel51 supports a pair of pin rings 55, one of which is a movable pin ring55A which can slide along the mandrel surface so the distance betweenthe pin rings can be reduced. Each pin ring 55 supports an annular arrayof twine loop anchor pins 56 which are equally spaced and which extendradially outward from the mandrel central axis 51B. A fixed pin ring 55Bis attached to the mandrel portion 51A which is removable and comprisesa structural portion of the removable axel member 54. A coupling formingapparatus 58 such as may be used to make a segmented type couplingstructure having the configuration shown in FIG. 32 or FIG. 33 issupported on the mandrel 51 between the pin rings 55.

FIG. 24 is a perspective view of a powered linear traverse apparatus 66comprising a floor-mounted powered sprocket drive 67 that moves an "L"shaped traverse structure 69 along a straight floor-mounted track 68that is at least twice the length of the traverse structure 69. Thetrack is preferably made from a steel 1"×1"×1/4" angle and comprises atleast one movable section 68A to permit passage of mandrel carriagecaster wheels 59A across the track line. The traverse structure isconstructed to be able to be attached to a movable mandrel carriagestructure 65 such as shown in FIG. 25. The traverse structure 69 and thecarriage structure 65 are both equipped with carriage attach apparatus65A that secures the carriage 65 to the traverse structure 69 to enablethe performance of a traverse operation of the carriage upon the track68. The traverse structure is equipped with a straight sprocket chain69A which is permanently attached to the driven side of the traversestructure and with at least three supporting "V" grooved caster wheels59A at least two of which ride on the track 68. The traverse apparatus66 is used to move a mandrel carriage 65 and the mandrel 51 supportedthereon past a fixed twine impregnation apparatus (not shown) such asschematically depicted in FIG. 44 to thereby enable placement ofcircumferentially disposed twines upon coupling forming apparatus 58.

FIG. 25 is a perspective view of a movable mandrel carriage structure 65on casters 59 that comprises a mandrel axel support 60, such as isformed from a pair of heavy duty roller bearings, a sprocket drive chain62 which rotates the mandrel 51 when driven by a motor 61, a hinged axelsupport structure 64 that allows removal of a finished tubular compositecoupling structure from the mandrel and a pair of adjustable mandrelsupport wheels 63 that supports the mandrel 51 during removal of atubular spring-lock type of coupling structure.

EXAMPLE VIII

FIG. 27 schematically illustrates the apparatus and method to make amatrix-impregnated twine 7 of helically configured strands 4 of filamentreinforcements 5 used to fabricate flanged spring coupler structureswhich embody the present invention. FIG. 27 also schematicallyillustrates apparatus used to form, tension and position loops of twine46 upon forming apparatus 58.

FIG. 27 further illustrates forming apparatus used to constructsegmented couplers having flanged curved composite spring members ateach end of a coupler body to provide a preferred embodiment of thepresent invention. The method and apparatus to make a twine of matriximpregnated helically configured strands containing unidirectionalfilament reinforcement comprises the following sequence of steps:

1. Position in adjacent proximity, preferably in a row, at least threepackages of continuous filament strands which have been helically woundto form a cylindrical strand package 50 having a central axis 50A.

2. Position above each strand package, preferably in a row, a circularstrand guide ring 90.

3. Pull a strand end from the inside and/or outside of each strandpackage in a direction parallel to the package cylindrical axis 50A.

4. Place each strand end through the strand guide ring located above thestrand package 50.

5. Pull the strand end toward a strand collecting funnel tube 53 locatedat one end of the row of strand guide rings, threading the untwinedstrand 4A through any and each adjacent strand guide ring comprising therow of guide rings aligned with the strand collecting funnel 91 to forma dry twine 7A comprising helically configured dry filament strands 4.

6. Pull the dry twine 7A through the strand collecting funnel end 91 ofthe funnel tube 53 bent and shaped to guide the dry twine cord towardthe top of a receptacle containing a liquid hardenable bonding matrix 6.

7. Pass the dry twine cord through the funnel tube into the matrixreceptacle 84A and under a smooth cylindrical impregnating bar 84Bpositioned near the bottom of the matrix receptacle to impregnate thedry twine strands 4 with the liquid matrix 6.

8. Pull the impregnated twine 7 up and out of the receptacle through apair of smooth parallel squeegee bars 92 rigidly positioned above thereceptacle and spaced sufficiently close to remove any excess of liquidmatrix from the twine.

9. Pass the twine 7 into a funnel-shaped twine cord compressing unit 93having an exit end orifice which is able to accept and compress amultiple of twines that have been similarly impregnated with the same orother compatible liquid matrix 6C.

10. Pull the twine cord 7B through the funnel tube exit orifice into atwine friction unit 94 comprising a set of three smooth adjacentparallel horizontal cylindrical bars arranged so the axis of each bar isperpendicular to the axis of the funnel tube exit orifice and so thatthe upper surface of the first twine friction bar is slightly beneaththe bottom of the exit end orifice.

11. Pull the wet twine cord 7B over the first friction bar 94A whichremains fixed and rigid and under the central friction bar 94B which isvertically adjustable to control twine sliding friction.

12. Continue pulling the twine cord 7B so it passes over the fixed thirdfriction bar 94C and under a smooth "U" shaped cylindrical tension bar95 having a weight at least equal to the weight of a desired length oftwine loop cord 46 and providing a means to maintain tension in thetwine cord 7B when the twine loop forming apparatus 86 is stationary orin motion on the return leg of a reciprocating traverse operation.

13. Pulling the twine cord 7B through the funnel end of a rigidtwine-directing exit orifice 96 positioned so the exit orifice axis isco-linear with the axis of the exit-end orifice of the twine cordcompression unit 93.

14. Pulling the twine cord 7B through a reciprocating twine loop formingand pulling apparatus 86 having the configuration and construction shownin FIGS. 26A and 26B and suspended from powered twine placementapparatus 97 comprising a continuous sprocket chain 97A supported ateach end by sprockets 97B, one of which is driven by a reversible motor97C. The twine loop forming and pulling apparatus 86 comprises a twinefunnel entry unit 87 and a twine exit orifice located at the end of aflexible tube 88 having a smooth interior and able to bend 180° in theplane containing the funnel entry 87 while providing a tube bend radiusat least equal to four times the average cross section diameter of thetwine cord 7B.

15. Securing the twine end to an anchor pin 56 attached to a fixed pinring 55B located at one end of a suitable coupler forming apparatus 58,said anchor pin located below the twine-directing exit orifice 96 and ata distance of approximately one meter from said orifice.

16. Activating the sprocket motor 97C and moving the loop formingapparatus 86 toward a second anchor pin 56 attached to a movable anchorpin ring 55A and located approximately parallel to the axis of the exitorifice 96 while simultaneously making and pulling freshly impregnatedtwine 7B from the twine exit orifice 96.

17. Making a tensioned loop of twine 46 while simultaneously increasingthe length of the twine loop 46 and moving the loop end formed by thebent flexible tube 88 toward the second anchor pin 56.

18. Manually stopping the loop forming apparatus 86 at a point as shownin FIGS. 29 and 34 where the exit end of the bent tube 88 has passed thesecond anchor pin 56 so the twine loop can be placed around the pinprior to the loop forming apparatus 86 moving in the opposite traversedirection. Alternatively, using a position sensor 98 to activate aremote relay 99 which halts motor operation for a fixed time intervalbefore starting motor rotation in a reverse direction.

19. During the time interval when the loop forming apparatus 86 isstationary securing the twine loop end to the second anchor pin 56 whichis attached to a movable pin ring 55A mounted upon a rotatable mandrel51 supporting coupling forming apparatus 58 such as shown in FIGS. 27,28, 29, 30, 31, 32, 33 and 34.

20. Rotating the coupling structure forming apparatus 58 which ismounted upon a mandrel 51 so as to move a third anchor pin 56 to theposition previously occupied by the first anchor pin 56 whilesimultaneously temporarily halting the making and pulling of amatrix-impregnated twine cord 7B and using the three-bar friction unit94 to lock the travers-return leg of twine 46A between the second anchorpin 56 and the three bar twine friction unit 94 as shown in FIGS. 30 and31.

21. Activating a traverse reverse-direction motor switch to energize thesprocket chain 97A to which the loop forming apparatus 86 is attachedand begin moving the loop forming apparatus toward the third anchor pin56 while simultaneously lowering the vertically reciprocating twine loopforming unit 89 to maintain tension in the traverse-return leg of thetwine loop cord 46A.

22. Continuing to move the loop forming apparatus 86 in its loweredposition along the return leg of the twine loop 46 while simultaneouslystraightening the flexible tube 88 as it trails behind as shown in FIG.34.

23. Stopping, such as by the automatic sensing and switching meansdescribed in Step 18 above, the loop forming apparatus at its originalstarting point when the twine exit orifice of the trailing flexible tubepasses beyond the third twine loop anchor pin as shown in FIG. 31.

24. During the time interval when the loop forming apparatus isstationary, looping the twine cord 7B around the third anchor pin 56 toanchor the return leg of the twine loop 46A.

25. Energizing the sprocket motor 97C to drive the sprocket chain 97A ina reverse direction while simultaneously raising the reciprocating loopforming unit 89 to allow the flexible tube 88 to bend 180° and clear thesurface of the forming apparatus 58 while the twine loop formingapparatus 86 proceeds to make a second loop of twine cord 46 and pull itfrom the exit orifice 96 as it moves toward a fourth anchor pin 56 asshown in FIGS. 28 and 29.

26. Repeating the steps of 17 through 25 above until all anchor pinsattached to the anchor pin support rings 55A and 55B have been used tosecure the twine cord 7B.

27. Stopping the loop forming apparatus at its original startingposition, looping and tying the return leg end around the first anchorpin 56 so it remains permanently secure, pulling a short length ofadditional twine from the exit end of the flexible tube and cutting thetwine at the anchor pin to provide a tail of twine emerging from the endof the straightened flexible tube.

FIGS. 26A and 26B are perspective views of the twine loop forming andpulling apparatus 86 used in the method describe above. This apparatuscomprises a funnel-shaped twine entry unit 87 attached to a flexibletwine guide tube 88 which is able to bend 180° to produce and pull atwine loop comprising longitudinal twines of filament strandreinforcements. The twine guide tube 88 is secured to a verticallyreciprocating member 89 that is connected by guide pins 89A to slottedsupport structure 89B having a pin guide slot 89C oriented at a 45°angle with respect to a horizontal plane and directed downward and awayfrom the funnel-shaped twine entry unit 87.

EXAMPLE IX

FIG. 44 schematically illustrates the method and apparatus by whichindividual strands of filament reinforcement 4A are helically configuredand impregnated to form twines 7 which are combined and flattened priorto being disposed as circumferentially oriented twines 8 upon anunderlying ply of longitudinally oriented twines 9 to provide themultiple ply construction of flanged cantilever composite spring membersthat may comprise a preferred embodiment of this invention. As shown inFIG. 44 untwined strands 4A are fed through strand guide rings 90 afterbeing pulled from roving packages 50 in a direction parallel to theroving package cylindrical axis 50A. The twine of dry strands 7A is fedinto a strand tube collecting funnel which comprises part of the twineforming apparatus 53. The dry twine of strands 7A is directed into atwine impregnating apparatus 84 comprising a receptacle for liquidimpregnating matrix 84A and a cylindrical impregnation bar 84B. The wettwines 7 are pulled beneath the impregnation bar 84B through twineribbon forming apparatus 85 comprising a twine width control member 91A,a pair of polished steel squeegee bars 92, and a twine ribbon feed bar91B, to provide a twine ribbon 7C having a minimum thickness generallyranging from 0.75 to 1.0 mm for twines made from roving having a yieldof 500 meters per kilogram.

EXAMPLE X

FIGS. 35, 36 and 37 illustrate in simplified schematic form the methodand apparatus for inserting the spigot-end body member 20B of aspring-lock type of coupling structure into the socket end 20A of aspring lock coupling structure 20. The coupling assembly apparatusschematically depicted in FIGS. 35, 36 and 37 comprises a removablesocket end anchor ring 101 which is secured firmly to the socket end ofthe coupling structure body member by such means as clamping or byengaging with an external bevelled flange 100A formed as an integralpart of the socket-end coupling structure body member. The couplingassembly apparatus also comprises a removable spigot-end anchor ring 102which is secured firmly to the spigot end of the coupling structure bysuch means as clamping or, as is shown in FIGS. 35, 36 and 37, byengaging with an external flange 100B formed as an integral part of thespigot-end coupling structure body member. The coupling assemblyapparatus also comprises pulling apparatus 1C by which the socket-endanchor ring 101 and the spigot-end anchor ring 102 can be broughttogether with a force which is sufficient to overcome the unit springdeflection force that is produced when the flanged composite spring 3 isdeflected to a height sufficient to permit entry of the spigot flangemember.

FIGS. 38, 39, 40, 41 and 42 illustrate in simplified schematic form themethod and apparatus for separating the spigot end 20B of a couplingstructure body member from the socket end 20A of a mating spring lockcoupling structure. A removable socket end anchor ring 101 is securedfirmly to the socket end of the coupling structure body member. Aremovable spigot end anchor ring 102 is secured firmly to the spigot endof the coupling structure body member. The anchor rings are broughttogether by such means as pulling apparatus 103. A removablepolygon-shaped ring structure 104 having an array of flat bevelled edgeswhich can engage and support the flange edge of each spring member ismoved and retained in position by a ring of individual wedge blocks 105having a width less than each spring member and equal in number to thenumber of flanged cantilever spring member comprising the couplingspigot end. The wedge blocks are loosely connected by an encirclingwedge block cord 106.

EXAMPLE XI

FIGS. 78, 79, 80, 81 and 82 exhibit a movable spring-lock couplingstructure 20 that can be fabricated to enclose one end of a compositepipe structure 29 having flanged joint ends adapted to accomodate acompressible annular face seal 38A.

FIG. 78 is a perspective view showing the position of a movablespring-lock coupling structure 20 when in the fully retracted positionillustrated in the perspective side elevation section view of FIG. 79.The movable spring-lock coupling structure, as with the segmcnted typecoupling structure described in Example V of the present invention,enables the connection of flanged-end pipe joints 29 having identicalends which are able to accomodate an annular face seal 38A. The movablespring-lock coupling structure is characterized especially by acylindrical body member 30 comprised of a second ply body memberconstituent 26 placed upon the cylindrical first ply body member 24Ahaving one extremity configured to comprise a polygonal array ofcantilever flat spring members 31 having a polygonal array of straighthinge lines 21 produced by a second ply polygonal shaped body memberextremity 26A. The first ply flange constituent 23 of each cantileverspring member is configured to provide a cylindrical-segment shapedfirst ply flange member 23A which engages the flange of a pipe joint 29.

FIG. 80 illustrates the position of the movable spring-lock couplingstructure with respect to pipe joint ends 29 in the process of beingconnected. In this position the movable coupling is fully extended toprovide a socket-end 20A of a spring-lock coupling structure.

FIG. 81 illustrates the position of the flanged pipe ends 29 when thearray of flanged composite cantilever springs 22 are fully deflected toenable the spigot-like entry of a flanged pipe end 29.

FIG. 82 illustrates the connection and sealing position of abuttingflanged pipe ends joined by a movable spring-lock coupling. Theencircling cylindrical composite retaining sleeve member 18A is used ina manner similar to that described in Example V above and deflects thebevelled flange load face which provides the prestress compression loadthat compresses the face seal 38A and provides deflection and pre-stressforces to the first ply flange member 23A which preferably exhibits afolded first ply flange body configuration 74.

I claim:
 1. A method for making a composite structure having alongitudinal axis comprising the steps oftwisting strands containingcontinuous filament reinforcements together to form a first ply twine sothat each of said filament strands extends in the direction of said axisto exhibit a center-pull helical frequency and configuration defined bya multiple of revolutions of said strands with each of said strandshaving helixes that are spaced relative to the helixes of the otherstrands in the direction of said axis, impregnating said first ply twinewith a hardenable adhesive means, securing a first end of said first plytwine to a first extremity of a forming surface, disposing a first twinelength of said first ply twine to extend in the direction of saidlongitudinal axis, suspending said first twine length across at leastone flange forming cavity of said forming surface, securing a first loopend of said first ply twine to a second extremity of said formingsurface, disposing a second twine length of said first ply twineadjacent to said first twine length, securing a second loop end of saidfirst ply twine to said first extremity, repeating the steps ofdisposing said first ply twine as a sequence of said adjacent twinelengths formed from the adjacent placement of a multiple of saidlongitudinal looped twines having said loop ends secured to oppositesaid extremities of said forming surface, securing a second end of saidfirst ply twine to the first extremity of said forming surface, twistingstrands containing continuous filament reinforcements together to form asecond ply twine of dry strands, impregnating said second ply twine witha hardenable adhesive means, applying said second ply twine transverselyacross said multiple first ply twine to impose a substantially uniformload thereon and provide a first ply hinge line edge, deflecting saidfirst ply twine into said flange forming cavity by said second plytwine, moving said loop ends of said first ply twine secured to saidsecond extremity of said forming surface toward said flange formingcavity, and placing said second ply twine upon said first ply twine totension and straighten said first ply twine.
 2. The method of claim 1further comprisingpressing said second ply twine upon said first plytwine to compact and deflect the underlying first ply twine into acantilever spring configuration having at least one flanged end,hardening said adhesive means to maintain said first and second plytwines in said cantilever spring configuration to form a flangedcomposite spring attached to a composite spring-connecting body, andslotting said flanged composite spring at least partialy in thedirection of said axis to form at least two independently deflectableflanged composite cantilever springs.
 3. The method of claim 2 furthercomprising closely compacting a plurality of said first ply twinestogether into a tubular configuration and forming a plurality of saidsecond ply twines into a second ply ribbon and wrapping said second plyribbon upon said first ply twines to form a tubular composite structurehaving an inwardly projecting flange on at least one end thereof.
 4. Themethod of claim 3 further comprising placing said second ply twines oversaid first ply twines so that the respective first and second ply twinesthereof are transversely oriented relative to each other within theapproximate range of from 80° to 90°.
 5. The method of claim 3 whereinsaid deflecting steps comprises deflecting said first ply twines intoeach of a pair of flange forming cavities located at opposite ends ofsaid forming surface.
 6. The method of claim 4 wherein said slottingstep comprises dividing said composite structure into a pair of at leastsubstantially identical semi-circular composite structures.
 7. Themethod of claim 3 wherein said disposing step comprises disposing aportion of said first ply twines upon a third ply of circumferentiallyoriented twined filament strands previously wrapped upon the extremityportion of said forming surface where said flange forming cavity isabsent.
 8. The method of claim 7 wherein said slotting step comprisescutting one end of said tubular composite structure to form an annulararray of independently deflectable flanged composite flat springs havingstraight hinge lines.
 9. A method for making a twine cord comprising thesteps ofpulling a multiple of continuous dry first filament strands froma multiple of first strand supply packages, said strands individuallycomprising a collection of at least approximately parallel continuousfilament reinforcements, twisting loosely together said first filamentstrands to form a first twine of unidirectional helically configuredfilament strands, impregnating said first twine filament strands with asurplus of hardenable liquid adhesive means to form a wetted firsttwine, pulling a multiple of continuous dry second filament strands froma multiple of second strand supply packages, twisting loosely togethersaid second filament strands to form a second twine of unidirectionalhelically configured dry filament strands, twisting loosely andsimultaneously compressing said first and second twines together to forma twine cord, impregnating by capillarity said dry second filamentstrands with the surplus of said hardenable liquid adhesive meansimpregnating said wetted first twine, and squeezing said twine cord toremove residual surplus liquid adhesive means therefrom.
 10. The methodof claim 9 further comprisingwrapping said twine cord around at leastone cylindrical friction producing member to configure said twine cordwith a wrap angle contact that imposes a uniform pull resisting loadupon said twine cord, pulling a first length of said twine cord in thedirection of said longitudinal axis while simultaneously twining andimpregnating an equal first length of dry filament strands, forming afirst loop in said twine cord at least approximately at the middle ofsaid first length, securing a free end of said twine cord to a firstanchor point located at the upper extremity of a forming surfaceadjacent to said friction producing member, moving said first loop endof said twine cord in a direction parallel to said logitudinal axis andtoward a second anchor point located at an upper opposite extremity ofsaid forming surface, and opposite said first anchor point,simultaneously pulling a second length of looped twine cord newly madeby pulling, twining and impregnating an equal second length of dryfilament strands, said second length being at least approximately equalto twice the distance between said first and second anchor points,gripping said second length of twine cord at the unlooped terminusnearest said friction producing member, securing said first loop end atthe middle of said second length of looped twine cord to said secondanchor point, securing said unlooped terminus of said second length oflooped twine cord to a third anchor point located at the opposite upperextremity of said forming surface, opposite said second anchor point andadjacent to said first anchor point, forming and pulling a third loopend of a third length of said twine cord in the direction of saidlongitudinal axis towards a fourth anchor point located adjacent to saidsecond anchor point while simultaneously twining and impregnating an atleast approximately equal third length of dry filament strands,simultaneously forming a second loop end of said twine cord at saidthird anchor point to form a three-point anchored length of said secondlength of twine cord and a single-point anchored length of said thirdlength of looped twine cord, gripping said third length of looped twinecord at the non-anchored looped end terminus of said length of saidthird length of looped twine cord, securing the pulled third looped endof said third length to said fourth anchor point, forming a fourth loopend at the terminus of said third length of twine cord and securing saidfourth loop end to a fifth anchor point located at the upper extremityof said forming surface opposite to said fourth anchor point andadjacent to said third anchor point, repeating a sequence of said priorsteps until a desired length of matrix-wet twine cord has been disposedupon said forming surface from which can be made a single ply compositestructure comprising at least one loop of said twine cord extending in adirection parallel to said longitudinal axis and comprising at least twoparallel twine cords comprising a single anchored loop end and two twinecord ends anchored at extremities opposite said anchored loop end. 11.The method of claim 10 wherein said forming surface is a rotatablecylindrical forming surface having an annular array of equally spacedadjacent anchor points located at each extremity of said rotatableforming surface and further comprising rotating said cylindrical formingsurface an angular distance equal to the angular distance between saidadjacent anchor points prior to the step of securing the unloopedterminus of said length of looped twine cord to said anchor point. 12.The method of claim 11 further comprising placing said longitudinaltwine loops in a predetermined position upon the uppermost portion ofsaid cylindrical forming structure immediately after the step of forminga loop in said twine cord.
 13. The method of claim 12 further comprisingrotating said cylindrical forming structure to place said fourth anchorpoint at the uppermost position on said cylindrical forming surfaceimmediately after the step of gripping said third length of looped twinecord.
 14. The method of claim 13 further comprising pressing andanchoring said longitudinal twine loops upon said cylindrical formingstructure in a sequential manner and pressing them against saidcylindrical forming surface after being anchored to said anchor pins toprevent said twine loops from sagging into catenary loops between saidanchor pins when said forming structure is rotated.
 15. A method forforming a composite twine structure having a longitudinal axiscomprising the steps ofimpregnating at least two filament strands, eachcomposed of a multiple of individual filament reinforcements, with afirst hardenable liquid adhesive constituent, twining together saidimpregnated filament strands in the direction of said axis so that saidimpregnated filament strands each exhibit a helical frequency andconfiguration defined by a multiple of revolutions of said strands witheach of said strands having helixes that are spaced relative to thehelixes of the other strand in the direction of said axis, and curingsaid liquid adhesives to form a hardenable bonding matrix maintainingsaid filament strands as said composite twine structure.